After an update groups are not working in OX-Appsuite

Dear Community,
after an update to univention 5.0-3 errata699 and Appsuite 7.10.6-ucs7 (OX-Connector 2.2.1) we have some issues.

When I edit an user in umc, you can see in the ox-connector.log that the user is written to the database.
If I edit a group, there also is an entry, that the group gets an update, but there is a message like: “Group wants uid=user-id, ou=ldap-schema, dc=server, dc=local as member. But the user is unknown. Ignoring…”.
If I look in the database, the user exists but is not in that group.

Does anyone have an idea?

Kind regards

I found out something:
We are also using the ad-connector to connect out windows active directory.

If I create a new user in the univention ad, the group assosication works.
If I create the new user in the windows ad and the ad-connector syncs the groups and users, the user is not in the OX-database but in UMC both users are member of the group.

Any ideas?

It seems like there is a problem with capital letters in the base dn.
If I create a new base dn that is written in lower case association of users to a group is running.
Is there an other opinion than renaming the base dn?

It seems like its a clone of this Bug: