After following KB article 48408 for attribute redirection
Whenever we set the NRM_MemAttr_Source to valid attribute and do a device reconfigure the NRM_MemAttr_Source will go back to ***not set*** even though the attributes are valid ones.
Release : 21.2.x, 10.4.x
Component : Spectrum Core / SpectroSERVER
The reason why the attribute redirection was not working for the Memory is because, by default, for Cisco devices, we use Cisco_Mem_App model, but in this case that app model does not exist.
Once this has been done, please set the NRM_MemAttr_Source back to Attribute Redirection and do another Device Reconfiguration.
This time the values will stay and after a few minutes you should start to get values in the Performance tab.