Additional sign-in or account-related issues within Microsoft Teams for business
Hi @Will Blade,
Since the Teams web app works correctly, your account and the Teams service are likely functioning normally. The issue is probably isolated to the local desktop client. While troubleshooting, you can continue communicating with your colleague through Teams on the web so your work is not interrupted.
In addition, please try the following troubleshooting steps:
First, try repairing the Teams app. Go to Settings > Apps > Installed apps, locate Microsoft Teams, select Advanced options, and choose Repair.
If Teams is still stuck on the loading screen afterward, try Reset, then restart your computer and sign back in. This will clear the app's local data and settings, but your online chats, teams, and files will remain unaffected.
If the problem continues, I would recommend completely uninstalling Teams, restarting the device, and then installing the latest version of the Teams desktop client from Microsoft: Download Teams Desktop and Mobile Apps | Microsoft Teams
It may also be worth checking whether your operating system is fully up to date, as pending updates can sometimes cause unexpected compatibility issues with Teams.
Please give these steps a try. If anything changes, or if you encounter any error messages along the way, feel free to leave a comment with an update. I'll receive a notification and will be happy to take another look and help troubleshoot further if the issue persists..
Thank you so much for taking the time.