Keycloak 18 to 19 - admin console - groups view is partly filled

Getting advice
1

Hey,
we just made an upgrade from keycloak 18 to 19.0.2.
No we noticed, that in /auth/admin/master/console/#/REALM/groups/ only four groups are displayed. There should be around 1500 groups.
But whenever I search in “search groups” /auth/admin/master/console/#/REALM/groups/search/, I find results from all groups.

Also loading of users groups takes forever:

image
image1646×814 34.7 KB

Any idea what we need to do?
Is there a kind of reindex?
Thanks!