Hello Guys.
We use SNMP Modular input to poll data from the devices. We use CISCO, added CISCO MIBs, then added IF-Mib. And after adding IF-MIB file on heavy forwarder in smp_ta folder, on ad hoc search head we see only 6 fields from IF-MIB (ifDescr_1,... ifDescr_6). When we do snmpwalk from heavy forwarder to the device, we see 87 fields with interfaces names. Seems there will be limits.conf, but maybe you had the same situation ?