OME discovery of VRTX R1-2401 switch

I have many VRTX devices all with the R1-2401 1Gb I/O module installed. There are no issues with the module and I can access it via both the web gui and telnet/ssh.

When I run a OME discovery on the VRTX CMC it pulls in all the inventory and status info for both the VRTX chassis and the installed M630 server blades however nothing for the R1-2401 switch module.

It writes this error to the OME logs:

Chassis Discovery Task: Switch IP (xxx.xxx.xxx.xxx) of CMC (xxx.xxx.xxx.xxx) has invalid community string. Skipping this Address

(ip address info removed)

Invalid community string suggests snmp is involved here however the discovery mechanism being used is WS-Man only and the check box is ticked for "Auto discover iDRACs and switches in the CMC"

All the firmware/software is the latest version on all devices. I have read through several Dell white papers on this and they all claim it just works via WS-Man through the CMC.

Any ideas as to why the switches are not being scanned in?

Many thanks

Dan