Side Scrollbar disappears frequently in the New Teams.

Same issue eexactly how you describe

Thank you for your explanation and workaround. This is exactly what is happening to myself even after a full uninstall and reinstall of new Teams. At least my spell check started to work again.

I installed this version https://staticsint.teams.cdn.office.net/production-windows-x64/24036.4400.2677.6911/MSTeams-x64.msix as this has no issue. It will ask you to restart to update the top right, don't do that as it will take you back to the troublesome update.

Until this is fix i will just use the above

In the New Teams App, I could see that the Scrollbar is getting disappear frequently.

Since February 5, 2024, I too can no longer use the scroll bar in the new Teams environment. I experience this as a big and serious problem. I urge Microsoft to restore the scroll feature soon. My argument is also ergonomic. Where a mouse with a scroll wheel is not used for ergonomic reasons, it must be possible to scroll with a normal mouse to protect the employee. That will only be possible if Microsoft restores functionality and brings back the scroll bar in the new Teams. I am counting on an urgent and rapid recovery action from Microsoft.

I have the same issue as well. In my opinion the "new" teams is significantly less reliable than the previous version. I'd stay with the old version, but the constant popups and stealth updates to the new version make that difficult.