Groups synced to AAD, but OWNER attribute is still empty. "Managed by" is also not available

Question

I have created several groups in AD and defined "Managed by" as well as OWNER in the attributes. The groups are synced to AAD, but looking to the Microsoft Entra Admin Center, I can see the group and the members, but no owner is shown. How can I get the "owner" or "managed by" information the set up a review process for these groups?

Thanks in advance