Word global template checkbox automatically unticked

Question

Environment : 70 users small office network, 4 x Citrix servers using Windows 2022 datacenter, MS 365

A few users, but not all of them, are reporting Word global templates checkboxes are unticked at launch (see image) but not all of them.

When the user tick the missing one and click on OK, global templates are still disabled and when re-opening the setting box (developper options) the tick are cleaned again (only the first and last one remaining).

All global templates are on the same drive (read only) and same folder.

Those users are not on the same server and other users on their server doesnt have the same problem.
Server redirection on login is based on server load. (user randomly change from a server to another each day).
Probably the problem is not server-based.
All users share the same GPOs, same settings, same rights.

After months of research on the net, I still have no clue how to fix this problem.

Thanks for any input !