Hi LBF MSFT
Good day! Thank you for posting to Microsoft Community. We are happy to assist you.
I am truly sorry for the inconvenience this issue has caused you. Based on the description, I understand that the chats reading pane has disappeared in Microsoft Teams. Instead, a gear icon is showing. The issue is happening in both Teams desktop client as well as the Teams web version.
To further clarify the issue, I would like to collect the following information. In order to protect your privacy, I will send you a private message. You may share the information by replying to the PM.
- Please kindly share screenshots of the issue for better understanding.
- Does the issue happen to anyone else in your organization?
- Please try to clear Teams cache by following: Clear Teams cache - Microsoft Teams | Microsoft Learn
Below are the steps to open private message:
- To View private messages option > click on Profile Picture at top of the right side > Select My Profile option.

Please understand that our initial response may not always resolve the issue immediately. However, with your help and more detailed information, we can work together to find a solution.
Your understanding and cooperation are greatly appreciated.
Sincerely,
Roger Shen