Hi @zhidong zhai ,
Welcome to our forum!
Based on my search on Outlook for Mac, it works well.
Do you have the latest updates installed on the computer?
Click Help> Check for updates and check if the problem gets resolved.
Besides, it is recommended you try creating a new profile, which will create a new database and re-download your email from the server. You can rename your old profile or set the new profile to be your default then re-add your account. See: Manage profiles or identities in Outlook for Mac
Hope this can help you!
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.