The short answer is that there appears to be an issue with RME managing a device running 11.0(22). The problem is the device is not returning the full OLD-CISCO-CHASSIS-MIB information needed to build the inventory containment for this 2501. RME is expecting additional objects to be returned which are not, and this causes an exception.
A similar bug was fixed before RME 4.0 was released, so this could potentially be fixed in RME as well without needing to upgrade the IOS. You should open a TAC service request so that a bug can be investigated.
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...