F5 was being polled by a server. Some of the OIDs were working while others didn’t work. Restarting snmpd didn’t help. Restarting both snmpd & subsnmpd solved the problem and all the OIDs were working again.
(tmos)# restart sys service snmpd
(tmos)# restart sys service subsnmpd
(tmos)# show sys service snmpd subsnmpd
snmpd run (pid 31980) 3 minutes, 4 starts
subsnmpd run (pid 927) 2 minutes, 1 restart
SOL8035 has information on the BigIP Daemons.