I got PHP-Notices like this:
Notice: Undefined index: id in /home/[...]/wordpress/wp-content/plugins/meta-box-aio/vendor/meta-box/meta-box-builder/src/Register.php on line 63
from Blocks built with MB Blocks. That was because I used the Layout Elements "Divider" and "Heading" in my Blocks and they do not get an id from the builder.
In the "Heading" Elements I could add an ID-Key with an unique Value in "Advanced" Custom settings. The Divider Element doesn't have Custom settings, so I had to delete them.