Weird save behavior {"Apple","Banana"} to null

Care to share some code?

Ok so the real issue seems to be the act of assigning this code to a variable as the page loads, permanently taints the variable, and it cant be saved into normally.

local!projectMouSubStatuses:if(a!isNullOrEmpty(local!projectMOU.statusId),
                                  null, 
                                  a!forEach(
                                    local!projectMouStatuses, 
                                    if((fv!item.description)=(local!projectMouStatuses[local!projectMOU.statusId].description), 
                                    fv!item.subStatus, 
                                    {}
                                  ))),

You can certainly save into a variable that is defaulted on form load, the exception is refresh variables with these settings cannot be saved into:

refreshAlways (Boolean): When true, the value of this local variable will be refreshed after each user interaction and each interval refresh. Because the variable is continually refreshed, you cannot update its value by saving into it. Default: false.

refreshInterval (Number (Decimal)): How often the variable value gets refreshed in minutes. When null, the variable will not be refreshed on an interval. Because the variable is periodically refreshed, you cannot update its value by saving into it. You can access the current value of the variable using fv!value (see the documentation for an example). Valid values: 0.5, 1, 2, 3, 4, 5, 10, 30, 60.

Ex:

a!localVariables(
  local!counter: 0,
  
  a!sideBySideLayout(
    items: {
      a!sideBySideItem(
        width: "MINIMIZE",
        item: a!buttonArrayLayout(
          align: "START",
          buttons: {
            a!buttonWidget(
              label: "Increment",
              value: 1+local!counter,
              saveInto: local!counter
            )
          }
        )
      ),
      a!sideBySideItem(
        item: a!textField(
          label: "Count",
          value: local!counter,
          readOnly: true
        )
      )
    }
  )
)

You can certainly save into a variable that is defaulted on form load, the exception is refresh variables with these settings cannot be saved into:

refreshAlways (Boolean): When true, the value of this local variable will be refreshed after each user interaction and each interval refresh. Because the variable is continually refreshed, you cannot update its value by saving into it. Default: false.

refreshInterval (Number (Decimal)): How often the variable value gets refreshed in minutes. When null, the variable will not be refreshed on an interval. Because the variable is periodically refreshed, you cannot update its value by saving into it. You can access the current value of the variable using fv!value (see the documentation for an example). Valid values: 0.5, 1, 2, 3, 4, 5, 10, 30, 60.

Ex:

a!localVariables(
  local!counter: 0,
  
  a!sideBySideLayout(
    items: {
      a!sideBySideItem(
        width: "MINIMIZE",
        item: a!buttonArrayLayout(
          align: "START",
          buttons: {
            a!buttonWidget(
              label: "Increment",
              value: 1+local!counter,
              saveInto: local!counter
            )
          }
        )
      ),
      a!sideBySideItem(
        item: a!textField(
          label: "Count",
          value: local!counter,
          readOnly: true
        )
      )
    }
  )
)