No worries, I am well aware that Pro doesn't do personal geodatabases and am in the process of converting what we have.
More to the point:
I don't have a GDB_Items table.
The only thing that lists all of them (feature classes, feature dataset) is GDB_UserMetadata
This is an .mdb, and ArcMap/Catalog correctly shows them as being inside the feature dataset.
I just opened up another, entirely unrelated MDB and have the same experience.
Why wouldn't they just be linked in a field in the feature class table, like, for example, Spatial reference is?
I'm very confused, here.
Edit: Apparently it's because these MDBs are from an earlier version. Once upgraded to 10, the items table appears. However, without upgrading them, how can it tell what they belong to?