Hi @Wu, Joanna PSA:EX ,
Please check the sent items setting by logging into the Microsoft 365 admin center, going to Teams & groups > Shared mailbox, clicking on the shared mailbox, and checking the option Copy items sent as this mailbox and Copy items sent on behalf of this mailbox
In addition, from your description, it is mentioned that the update of Teams integration may cause this problem. To further confirm, does the problem still exist if the add-in is disabled?
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.