Hi @AB123 ,
Regarding your issue, since it is only occurred in OWA, you can try the following suggestions:
- Clear the web browser cache then reboard again, or try another browser.
- Check if there is any Address Book Policy listed in Exchange Admin Center. https://learn.microsoft.com/en-us/exchange/troubleshoot/administration/cannot-browse-groups-in-owa
- Also kindly check if other users in your organizations are facing this issue or not.
If the issue still exists, please verify if there are any alerts in M365 Admin center and kindly provide more information.
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.