Using store engine fields with Profile module and inline forms is problematic

There seems to be a deeper problem involved here. Because after updating to D10 I cannot save even entities with referenced storage engine items anymore. It just complains. See screenshot.

I have no idea why only me has this problem. But something is messed up and I expect the ValidReferenceConstraintValidator.php be part of the problem. I CAN create a storage_data entity, BUT I cannot reference it in another entity. The Validator messes up the valid_entity_ids with the invalid IDs and thus it complains all day long.

I checked my other entities which reference to storage_data fields. And ALL have somewhat broken references.

It seems that something at some magic place went wrong, because when I create a second field which references to the same storage_data entities it works finde.

I now have to find a way to fix everything without loosing data.

Btw. no pending update db or entities updates are in queue. Everything is uptodate.

Just as a note. If I remove the field from the entity and re-create it with the exact same data AND after that import via SQL the original data into the db. Everything works.

Which leads me to believe that something in the Drupal registry about the storage_data fields is messed up. But because it is Drupal I have no idea where that is and I cannot give advice what to do without deleting and recreating the same data. :-(

To reinterate: I made a Drupal 9 to 10 update prior to this problem.

OMG I found a solution. Maybe it is helpful to someone. After Updating to Drupal 10, Drupal lost the *Reference Method* of the Entity. It told me that the selection handler is broken. It could also be, that the uninstall of WMBert as a WIDGET! was the cause. I don't know. Anyways, when I change it to default and pick the correct Entity (storage data) then everything works as expected. (See both screenshots)