Issues with value and saveInto parameter in a!checkboxfield()

I suggest to follow a structured problem solving approach. Reduce the code to the bare working/non-working minimum to understand what is going wrong. Then fix it and build back up to the final solution.

a!localVariables(
  local!question: split(rule!MWJ_qe_multiCorrect_fetchQuestion(), ";"),
  local!option: split(rule!MWJ_qe_multipleCorect_options(), ";"),
  local!numberOfAnswers: 4,
  local!correctAnswer: rule!MWJ_qe_MultiCorrect_CorrectAnswer(),
  local!selectedAnswer: rule!MWJ_QE_MultiCorrectOption_SelectedAnswer(),
  local!Temp: stripwith(
    local!selectedAnswer.SelectedAnswer,
    "ZYWX[]:"
  ),
  /*local!result: intersection(local!correctAnswer, local!Temp),*/
  /*local!score: length(local!result),*/

  local!submit: false,
  {
    a!sectionLayout(
      label: "xxx",
      contents: {
        a!forEach(
          items: local!question,
          expression: a!localVariables(
            local!currentQuestion: fv!index,
            {
              a!columnsLayout(
                columns: {
                  a!columnLayout(
                    contents: a!checkboxField(
                      choiceLabels: {
                        a!forEach(
                          items: enumerate(local!numberOfAnswers),
                          expression: index(
                            split(stripwith(local!option, "[]ZYWX:"), ","),
                            if(
                              local!currentQuestion = 0,
                              fv!index,
                              fv!index + local!numberOfAnswers * (local!currentQuestion - 1)
                            )
                          )
                        )
                      },
                      choiceValues: {
                        a!forEach(
                          items: enumerate(local!numberOfAnswers),
                          expression: index(
                            split(local!option, ","),
                            if(
                              local!currentQuestion = 0,
                              fv!item,
                              fv!index + local!numberOfAnswers * (local!currentQuestion - 1)
                            )
                          )
                        )
                      },
                      label: fv!index & ".  " & fv!item,
                      labelPosition: "ABOVE",
                      value: local!selectedAnswer.SelectedAnswer[local!currentQuestion],
                      saveInto:
                      a!save(
                        local!selectedAnswer.SelectedAnswer[local!currentQuestion],
                        save!value
                      ),
                      validations: {}
                    )
                  )
                  
                },
                alignVertical: "TOP"
              ),
              a!sectionLayout(
                label: "",
                contents: {
                  a!richTextDisplayField(
                    label: "Correct Answer : ",
                    labelPosition: "ABOVE",
                    value: a!richTextItem(
                      text: {
                        a!forEach(
                          items: local!currentQuestion,
                          expression: index(
                            local!correctAnswer,
                            if(
                              local!currentQuestion = 0,
                              "",
                              fv!index + 1 * (local!currentQuestion - 1)
                            )
                          )
                        )

                      },
                      color: "POSITIVE",
                      size: "MEDIUM",
                      style: "EMPHASIS"
                    ),
                    showWhen: local!submit

                  )

                }
              )

            }

          )
        )
      },
      marginBelow: "STANDARD"

    ),
    /*a!timeDisplayField(*/
    /*label:"Time Lapsed",*/
    /*value:time(now())*/
    /*),*/
    a!buttonArrayLayout(
      buttons: {
        a!buttonWidget(
          label: "Check Score",
          icon: "thumbs-up",
          iconPosition: "END",
          saveInto: {

            /*a!save(local!submit, save!value),*/
            /*a!save(ri!score.score,local!score)*/
          },
          /*submit: true,*/

          style: "GHOST"
        ),
        a!buttonWidget(
          label:"close",
          value:"close",
          saveInto: ri!buttonAction,
          submit:true,
          style: "SOLID"


        )

      },
      align: "CENTER"

    ),
    a!sectionLayout(
      labelColor: "POSITIVE",
      contents: {
        a!columnsLayout(
          columns: {
            a!columnLayout(
              contents: {
                a!richTextDisplayField(
                  labelPosition: "ADJACENT",

                  value:{a!richTextItem(
                    text: "Your Score is  ",
                    color: "ACCENT",
                    size: "LARGE",
                    style: "STRONG"

                  ),
                  a!richTextItem(
                    /*text: { local!score },*/
                    color: "ACCENT",
                    size: "LARGE",
                    style: "STRONG"


                  )},
                  showWhen: local!submit,
                  marginAbove: "STANDARD"

                )
              }
            )

          }
        )
      },
      isInitiallyCollapsed: true,
      dividerWeight: "MEDIUM",
      dividerColor: "ACCENT",
      marginAbove: "STANDARD"
    )


  }
)

 Hello Jai_1441 

Get the choice labels and choice values in a local. I would not recommend running it directly in the components.
Then when you have the code, please do post it here as Stefan has mentioned for a better readability.

I tried this same using a!map and it also worked perfectly fine. 

a!localVariables(

  local!InputData: {
    a!map(
      Questions:"What is CDT",
      Options:{
        "a",
        "b",
        "c",
        "d"
      },
      Selected:null,
      CorrectAnswers:"b"
    ),
    a!map(
      Questions:"What is expression",
      Options:{
        "e",
        "f",
        "g",
        "h"
      },
      Selected:null,
      CorrectAnswers:"g"
    ),
    a!map(
      Questions:"What is Interface",
      Options:{
        "i",
        "j",
        "k",
        "l"
      },
      Selected:null,
      CorrectAnswers:"k"
    )
  },
  local!SelectedAnswers:local!InputData.selectedAnswers,
  /*local!CorrectAnswer:local!InputData.CorrectAnswers,*/
  /*local!Results:{intersection(local!CorrectAnswer,local!SelectedAnswers)},*/
  /*local!Score:length(local!Results),*/

  {
    a!sectionLayout(
      label: "Quize Paper",

      contents: {

        a!forEach(
          items:local!InputData,
          expression: {
            a!checkboxField(
              choiceLabels: fv!item.Options,
              choiceValues: fv!item.Options,
              label: fv!item.Questions,
              labelPosition: "ABOVE",
              value:fv!item.selectedAnswers,
              saveInto: {
                a!save(fv!item.selectedAnswers,save!value)
              },
              choiceLayout: "STACKED",
              validations: {}
            )
          }
        )
      }
    ),
    a!richTextDisplayField(
      labelPosition: "COLLAPSED",
      value: {
        /*local!Score*/
      }
    )
  }

)

I don't see any error for the above code, other than having no context of the answer. 

I understand. The difference between a radiobuttonfield and a checkboxfield is, that checkboxes always return a list. That might break same related logic in your code.

Actually am fetching the choice values & choice labels from DB. If I am taking it from local than it worked fine only.

Yes, I meant running your expression rule or the iterations. This helps you understand what's going wrong in the locals.

Yes correct. thats why am saving the selected values using a!map() in rule rule!MWJ_QE_MultiCorrectOption_SelectedAnswer() to return a list. But still not able to save the selected values.

a!localVariables(
  
  local!count:count(split(rule!MWJ_qe_multiCorrect_fetchQuestion(),";")),
  local!selectedAnswer:
  a!forEach(
    items:enumerate(local!count),
    expression:

    a!map(
      /*Question:local!question[fv!index],*/
      SelectedAnswer:null,
      DummyAnswer:null
    )),
    local!selectedAnswer,
)