I've got host group inheritance like this:

PROJECT/LOCATION/ENVIRONMENT 

Full tree looks like this:

AAA
AAA/BBB
AAA/BBB/C1
AAA/BBB/C2
AAA/DDD
AAA/DDD/C1
AAA/DDD/C1

All servers are contained in the last groups with full path (AAA/BBB/C1)

Host groups AAA , AAA/BBB , AAA/DDD  are created, but empty.

And on the Monitoring ---> Latest data page . Filter does not allow me to select any of this parent group.