In case any of you are experiencing this issue (when the max user count hasn’t actually been exceeded) - it appears to be triggered by EDD, and there is no fix available yet. We are using E10 Public Cloud.
As per Tech Support:
Thank you for providing the most recent data–it was what allowed us to determine that this behavior is a known issue to our development team. The software change request is open with our development team, but, there is not an ETA on when a software change may be available as they are in the research phase of the R&D process. It will most likely not be changed by the time ERP 10.2.600 is released next month. The workaround until this change is implemented into the application is to log into the client either into the classic menu or modern (not active homepage), and use only the classic ERP forms instead of any of the new Kinetic versions. Linked is a knowledge article on how you can disable kinetic forms for a user account for your review. Please let me know if you have any questions Knowledge Article KB0090087 - Opt out of Kinetic forms for an individual user account (10.2.500)