The reason you're not seeing the missing devices in this group is because Campus Manager is not managing them. This can be caused by incorrect ACS integration, unsupported device types, or by a known bug.
If you are not integrated with ACS, and you know the device types are supported by Campus Manager 5.0.3, an upgrade would be the best course. Your version of LMS is quite old, and known to be affected by at least three bugs which would cause the symptoms you're seeing. You can freely upgrade to LMS 2.6 SP1 which includes Campus Manager 4.0.11 which fixes all of these bugs.
As a temporary workaround to the problem, you can try reinitializing the ANI database, then performing a new Data Collection. This should get Campus to manage the missing devices, but the problem will come back. To reinitialize the database run:
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...