"Share to Teams" not appearing in Outlook App
>Open Outlook
>File 
>Options 
>Add-Ins 
>At the bottom of the new window, switch "Manage: COM Add-ins" to "Disabled" 
>Select "Go..."
> You should see the Teams plugin listed here:
>Select it and click "Enable". Restart Outlook and the Teams icon should return and be useable. 