This is exactly as designed. The only reason the 'Reason and Process popup window' appears is because you have not already entered a Reason and/or Process in the main window. However, once you have entered values for both of these (either in the 'Main window' or via the 'Reason and Process popup window') then the popup window won't need to appear again.
The only reason the popup window was created in the first place was because it is not possible to stop the user splitting a polygon in GIS and then clicking 'Get Map Selection' before they have entered a Reason and Process. Because the tool then recognises a physical split is in progress and wishes to complete the job, it has 2 options:
1. Show the 'Reason and Process popup window' prompting the user to enter the missing value(s).
2. Show a warning message that the values are missing and do not complete the physical split.
Option 1 was chosen by the developers. Option 2 could be implemented instead but there is more risk that the physical split is not completed.
Ecologist & IT consultant
Andy Foy Consulting (ex-HBIC)