Symptoms

Update method not getting List View column calculations fast enough before saving.
 

Diagnoses

The final Save button calls the List View's Save Toolbar Button method before Update List Items on the main view. In runtime, it appeared that the "apply the changes to the row" action was happening too slowly, and the calculated field was not getting updated before the Update List Items method executed, thus saving the previous value.
 

Resolution

Instead of transferring data from the calculated field's Data Label to the main View's relevant Text Box control and then saving, we moved the Update List Items action to the Form-level, so that we could save the calculated value's Expression directly. In the Save Toolbar Button method, we added a transfer data from the calculated value's Expression to the main View's Text Box so it would update the value in the foreground.

Directly saving the expression like this is likely a lot faster and more direct than passing data around to controls beforehand.