TL;DR
Do you have something like (I’m assuming snmpd.conf):
smuxpeer .1.3.6.1.4.1.674.10892.1
The bridge isn’t going to work without that.
I’m talking about reading the “host” data via snmpd running on the host using the bridge to Dell stuff (that is, no direct iDrac query from CheckMK, just snmp).