OS: Windows 10
Acrobat Pro DC v2022.002.20191 | 64 bit

Steps to reproduce:
- open a PDF form with custom JS for textfield calculations
- activate form tools
- select a textfield and open properties / calculation
- JS is at the custom field (bottom)
- close the dialoge window
- repeat it with other textfield (open/close)
- repeat it with the first textfield
- (optional) repeat it multiple times

observed result: with a ~50% chance the (saved) JS code is gone
expected result: JS code should be not deleted

looks like a windows problem, no problems on MAC so far!