Hi Charlie,
Thank your for your reply and all the troubleshooting step you did so far.
Since you have tried all the steps, clean the Teams cache, re-assign the license, could we confirm with you when did this issue occur? You have mentioned your organization was not so actively used Teams before, in which means all users in organization suddenly got that kind of error message and cannot use Teams recently?
In addition, for the re-assign the licenses part, could we double confirm with you if your admin set at the Settings-Service & add-ins. You need to wait for sometime till it takes effect and need to check back.
In addition. make sure at azure.microsoft.com Enterprise application- all application>Microsoft Teams-properties the enabled user sign-in
If the issue still persists, we will continue investigating if it is a common phenomenon recently.
Let us know if it helps, thanks.
Kind Regards,
George
