I was wondering if it's standard behavior that users synched from local AD to AzureAD are not surfaced in the Teams Admin Center -> Users.
For us, only users created online and that have an @onmicrosoft.com email address are shown here.
We would like to be able to apply Teams policies to individual users but are unable to do so because of this.
Since I cannot assign a policy to an on-prem user I tried to check if changing a setting in the global out of the box policy has any effect - it does not seem so. For example, I deactivated the ability for users to delete messages. For an .onmicrosoft.com user it did take effect but not for an on-prem user.
@adam deltinger, AD sync has been working fine, the sync from on prem to AzureAD is executed every 30 minutes and I couldn't find anything wrong with it. All other O365 services seem to work fine.
However, I have a strong hunch what could be related to this issue. A couple of weeks ago our Skype on prem team had issues with federation with external Skype for Business Online users (presence states and such). So they disabled the 'CSOnlineSipDomain' like explained here: Disable-CsOnlineSipDomain. I believe what that did, at least I saw when the Sfb Online admin center was still around, was that it removed all registered Sfb Online users. So since Teams and Sfb Online Admin Centers are now one, perhaps this is why I'm not seeing our on prem users here anymore.