Little background on the problem. A while back, prior to our migration to Office 365, a distribution group was created on our on-premise Active Directory (for reasons unknown, it was actually created as a security group but was being used like a distribution group). Regardless, it wasn't showing up in Office 365. We went through and converted it from a security group to a distribution group and after updating the displayName attribute with the correct value, we were able to get it to synchronize from our on-premise AD to the Office 365 ECP.
The problem we have is that there is one user who we cannot get to show in the distribution group membership list when it's viewed in ECP. The user object is present in the on-premise Active Directory as well as in the membership list in the specified distribution group when we view it on the on-premise server, but it is missing when viewing the distribution group through ECP. Directory Sync does not seem to be throwing any errors on either the user object or the distribution list object.
Any help on what to look at next would be greatly appreciated!
