This is more or less an FYI. We’ve been upgrading to N9K from NX-OS 9.3.9 to 10.4.5 and have noticed ARP entries in LibreNMS from those switches disappearing. I’ve done SNMP walks and it appears this is a Cisco problem, as ipNetToMediaIfIndex is only showing entries from default VRF. I have a TAC case open with Cisco.
Edit 03-18: Cisco TAC is still investigating and labbing up N9Ks for testing.