I had mentioned in a previous post about the inability to self service groups.

Problem: on-premises distribution group is synced to a Microsoft Office 365 organization through Active Directory synchronization, migrated users who are owners of the distribution group can’t manage it in Microsoft Exchange Online

Solution: Use the Exchange Tools (But we no longer have exchange on prem?)

Solution: Use Active Directory Users and Computers

Solution: Dsquery.exe  – Press the Windows Key and R to open the run box and past in the following:

Owners of the group should be able to make changes when needed.

Note:  You will still need to wait for dirsync to complete.