Can't save any plugin settings- any ideas?

Logging in as new user does not exhibit this same issue.

Back in my actual User account: Trashing preferences for Nuendo, as well as deleting the Audio folder in the home library does not solve the issue.

When re-launched, Nuendo re-creates the Audio folder in the correct place: home/library/audio/(specific plug-in) but can’t actually create the saved file within that folder.

What else can I try, or what can I delete to take this version back to its original launch state, as it is with a new user?

Thanks so much.
PJ