we're running a hybrid infrastructure with Exchange Online and Exchange 2016 and Exchange 2010. We already moved a few hundred users to Exchange Online and everything is working fine.
During the last weekend we moved some additional users. Even though this worked fine too we are having the issue that their mailbox is not being shown in the Office 365 admin center. When opening a users settings and clicking on mail, everything looks like if the mailbox had not been migrated yet with not showing any permissions and displaying all apps as off:
Usually it should look like the following:
Trying to change mailbox settings using the admin center will produce error messages like "Couldn't update mailbox automatic replies info" when setting an auto reply:
Performing administrative tasks against the mailbox using Exchange Online Shell or with in the EAC works fine though and there are no other operating issues.
Does anyone have an idea what might be the problem here?