Hi Gaby
For OpenText you might need to run a trace. There are a few VIM objects to restrict but not sure which apply.
The VIM Workplace transaction is more of a cockpit and has the items appear for you based on the Chart of Authority setup and work centre assignments (less about standard SAP authorisations and PFCG roles). Although, it seems like you can switch team inboxes or other members. If you drill into a document I think the FB03 type authorisations come into play
I do recall running ST05 trace for SQL and coming across an OpenText/VIM configuration table which had some paramters. I never got a chance to test if any of these would limit access
Suggest you run STAUTHTRACE to see what is picked up.
Regards
Colleen