Field does not update for a certain record

Field does not update for a certain record

I have a field (Overlapping_Search_Profiles) on a form (frmSearch_Profile) which for one record does not update when I do this:

colSP.Overlapping_Search_Profiles = "";

and the record is part of the collection.

I already checked if the record actually is included in the collection.

Zoho has Edit Access.

To reproduce do this:
1. In my app (bmpm) go to the section 'Admin'
2. Open the view 'Export View: Profiles'
3. Search for the records with 'aer' in the 'Player' column
4. Open one of the two records and save it (in the on success action the function TestFunc4 will execute)

Regards,
Filip