@colegota I tried to add new account in # v.50.01, and I cannot do this either.
Actually, I'm using v.50.01 now and didn't notice any other problems yet. But I didn't add new accounts since last upgrade.
So existing users seems like unaffected by this bug.

Will fix the latest version as soon as I will be at my PC (I'm still faraway...)

For the new users:
1. Please uninstall v.50.01,
2. Install v.49 using G-Droid/F-Droid app. I just tried G-Droid, see screenshot - three versions of AndStatus are available. https://f-droid.org/en/packages/org.gdroid.gdroid/
3. Add all necessary accounts.
4. Create a backup in AndStatus Settings -> Storage -> "Back up app data to SD card".
Backups are always good, and in a case step 5 fails you can quickly restore everything, reinstalling v.49 and then Restore this backup from the first screen of the app.
5. (optionally) Update AndStatus to v.50.01 in the same G-Droid/F-Droid app. # misbehaved here for me on a first attempt... but after I had restarted it, it updated AndStatus successfully. https://loadaverage.org/attachment/5398183