Changing main region (Stammbezirk) not possible anymore.

Summary

Before the last release, it was possible to change the main region of an FS.

Steps to reproduce

1. Open an profile edit. E.g. mine: https://foodsharing.de/?page=foodsaver&a=edit&id=116481
2. Hit "Bezirk ändern"

What is the current bug behavior?

No regions can be selected:

What is the expected correct behavior?

Should look like before that release. (A tree view of the possible regions)