If you're not seeing the latest messages or threads in your Teams chat list, here are a few things you can try.
Restart Teams to force a refresh.
On Windows, navigate to your Taskbar and look for the Microsoft Teams icon. Right-click the icon and choose Quit. This will force the Teams app to quit. When it restarts, you should see your latest messages again.
On a Mac, force quit the Teams app by using the following keyboard shortcut: Option, Command, Esc. You also can navigate to the Apple menu, select Force Quit... and then choose Microsoft Teams from the list of open applications.
Check your internet connection to make sure it’s working by opening a browser and visiting any website.
If you’re using the Teams desktop or mobile app, try using the web version: https://teams.microsoft.com/.
Sign out of Teams by selecting your profile picture at the top right of Teams and then selecting Sign out from the menu options. Once Teams closes, open it again and sign in with your email and password.