Get DB data from a form called in a long process seems not working

I need to see actual code to fully understand what you are doing here.

The code of our Customer is very big and private, so I've created a little example:

Here is the main form call by a little process which contains only an User Input Task :

a!localVariables(
  local!model: null,
  {
    a!sectionLayout(
      label: "Vehicle",
      contents: {
        a!columnsLayout(
          columns: {
            a!columnLayout(
              contents: {
                a!textField(
                  label: "Vehicle id",
                  value: ri!vehicle.id,
                  labelPosition: "JUSTIFIED",
                  readOnly: true
                ),
                a!textField(
                  label: "Model",
                  value: ri!vehicle.model,
                  saveInto: {
                    ri!vehicle.model,
                    a!writeToDataStoreEntity(
                      dataStoreEntity: cons!CJT2_Entity_Vehicle,
                      valueToStore: ri!vehicle,
                      onSuccess: {
                      }
                    ),
                  },
                  labelPosition: "JUSTIFIED",
                  refreshAfter: "UNFOCUS",
                  validations: {}
                ),
                a!textField(
                  label: "Model from DB",
                  value: local!model,
                  labelPosition: "JUSTIFIED",
                  readOnly: true
                ),
                a!cardLayout(
                  contents: {
                    a!textField(
                      label: "Get DATA form DB",
                      readOnly: true
                    )
                  },
                  style: "INFO",
                  link: a!dynamicLink(
                    saveInto: 
                    a!localVariables(
                      local!vehicle: rule!CJT2_GetVehicleById(
                        id: ri!vehicle.id
                      ),
                      if(
                        a!isNotNullOrEmpty(local!vehicle),
                        a!save(local!model, local!vehicle.model),
                        null
                      )
                    )
                  )
                ),
               
              }
            ),
            a!columnLayout(
              contents: {}
            ),
            a!columnLayout(
              contents: {}
            )
          }
        )
      }
    ),
    
    /*Buttons*/
    a!sectionLayout(
      contents: {
        a!buttonLayout(
          primaryButtons: {
            a!buttonWidget_23r3(
              label: "Save",
              icon: "check",
              saveInto: {
              },
              submit: true,
              style: "PRIMARY",
              disabled: false,
              showWhen: true
            )
          },
          secondaryButtons: a!buttonWidget_23r3(
            label: "Cancel",
            value: true,
            saveInto: ri!cancel,
            submit: true,
            showWhen: true,
            validate: false
          )
        )
      }
    )
  }
)

- Enter a new vehicle model (the model is immediately saved in DB)

- Click on the "Get Data" Button to get the new data from DB : does not work and retrieve the previous data

Just a shot in the dark, are you using a combination of data store entity and records when you write/get? One thing that could cause the issue is writing with data store entity and retrieving with an unsynced record.

No, we do not have Record sync. And my little example does have any either

This might be because of that unnecessary local variables in line 49. Please try to add a refreshVariable on that local!vehicle and set refreshAlways to true.

Thank you Stefan, you're right

Hum, I'm understanding now, it is not a local variable issue but the default behaviour of the Appian localVariable function,

I had forgotten that detail 

Cool! Local variables can introduce a unexpected caching behaviour in certain situations. E.g. when writing expressions to encapsulate a API query, I try to avoid locals or at least add refreshAlways to make sure that API call actually happens, even when passing the same set of parameters.

Yes indeed, few years ago, I had already encountered this kind of difficulty, it just comes back to me.
Thank you for this advice