access copy and paste issue

We have a strange intermittent issue in an Access 2016 database application (classic architecture with individual front end per user with links to a central backend database), that prevents users copying text from emails, word docs, xlsx spreadsheets etc and pasting it into any field on any form in the database. It also prevents the copying and pasting text out of the records in the database out to other external files or blank emails etc. Access 2016 is installed on a Citrix XenApp server – this only seems to be an intermittent issue, and doesn’t affect other copy & paste operations in other desktop apps during the same sessions. Any ideas if this could be a specific setting/restriction in the access database/access itself, where I can check to see if that is the problem? Or any other broader windows type restriction?

We have had issues in the past whereby office seems to temporarily forget we have valid office licences and this causes all sorts of peculiar symptoms in office apps including access, but that was mainly around creating & updating records, not copy and paste in/out.