Azure "External Identities" -
We setup up cross-tenant organziation with another source tenant. You MUST use either a group or uid - we used a group.
The organization sync'd but the 'users' are in ID format, not username. No entry in AAD users. I waited 24 hours - still nothings. The UID is not very helpful as you can't do anything just because you have this ID.
Is there an undocumented setting or approach to make these users - AD connected from Tenant A to Tenant B properly show up?