i had a similar problem with a C9500. Was a bug in the IOS-XE.
The SNMP agent crashed when accessing certain OID.
This should be visible in the (debug) log. If so you can then
blocked the corresponding OIDs in the SNMP view like this:
snmp-server view **notALL** iso included
snmp-server view **noatALL** ciscoMgmt.771.1.1.2 excluded
snmp-server view **notALL** ciscoFlashFileEntry excluded
snmp-server group XXXXX v3 priv read **notALL**