Microsoft To Do login issue and missing tasks across platforms

Hello,
I'm currently experiencing a serious issue with the Microsoft To Do app on Android. Suddenly, it started prompting me to log in again. After logging in, it goes into an endless loading loop and keeps asking me to log in repeatedly.

I tried logging out and back in, but the issue persists. I then checked the PC version of the app, and strangely, none of my To Do lists were visible. When I accessed the web version, it just says “Preparing your lists...” but nothing ever loads.

Has anyone else experienced this issue or found a solution?
For context, I did recently make some changes to my account’s security settings—wondering if that might be related.

Thanks in advance for any help!