Many issues with Teams functionality can be addressed using the information in the links below.

1. Check for known issues in the new Microsoft Teams desktop client. (external link)
   
   
2. To solve most Teams' issues, clear your Teams application's cache. (external link)
   
   
3. How to restore Teams presence in Outlook.
   
   
4. How to restore Outlook's Teams add-in (external link) if it goes missing.