Additional assignment-related features and issues within Microsoft Teams for Education
Hi Enceladus, my name is Jose. I'm a Teams user like you and I'm glad to assist you with this issue.
In order to fix, please let's cleanup the Teams cache. Please uninstall Teams, then using the File Explorer go to %APPDATA%\Microsoft\Teams and remove every file and folder. Finally, install Teams again and try.
Please let me know if you need anything else.