Upgrade from 10.1.0 to 10.2.1 - Snmp issues

Are you walking it locally on the BIG-IP or remotely? If remote and and you don't have the F5 mibs installed this won't work, you'd need to use the actual oid string. Walk it from localhost on the BIG-IP and see if you get the same response. Otherwise I'd get a case open with support so they can assist your efforts.