Additional features, settings, or issues not covered by specific Microsoft Teams categories
Hi Michael,
Thank you for posting your issue on Microsoft Community. You may try to create a new Windows 10 user account and performing a clean install the latest Teams client to see whether the problem still occurs.
If you still having problem please provide us with the detailed Teams logs files via the Private Message for further analysis.
About the OneNote error there is temporary changes OneNote in Teams will be read-only for commercial tenants, excluding EDU. Users can go to OneNote for the web for editing. Download size and sync frequency of file attachments has been changed. You can find details on these and other OneNote related updates in the link: Awareness of temporary adjustments in Microsoft OneNote
Regarding this point, we would truly appreciate your kind understanding.
Best regards,
Shyamal