Date Calculation (onChange function) gives funny results

[Leo831-ux]

The setup is fairly simple with the 2 fields below

start_time - date/time field
end_time - date/time field

I then have an onChange call on the end_time to calculate the time difference in human readable format with the JavaScript

When using for the first time, the result comes back as an ISO string. If I click the end_time for a second time, then calculation returns the expected result. Changing the end_time again, then the result is not the expected result, i.e.

1. start_time = 01/10/2024 11:00
   end_time = 02/10/2024 11:00
   result = -479938.17

2. start_time = 01/10/2024 11:00
   end_time = 02/10/2024 11:00
   result = 24.00

3. start_time = 01/10/2024 11:00
   end_time = 03/10/2024 11:00
   result = 24.00

4. start_time = 01/10/2024 11:00
   end_time = 04/10/2024 11:00
   result = 48.00

I am using Cloud v2.32.9

Below is the app

TimeCalc-export-1727774386922.tar.gz