Solved - I’ve since been told this Cube actually has changes to the internal architecture and is not supported by PX4 yet.
I’ve been working with the Orange Cube+ and successfully making FW for it. Someone handed me an Orange Cube+ IB and it seems like TELEM1 and TELEM2 don’t work. I.e. everything works on the Cube+, swap the same FW, parameters, equipment and wiring harness to the IB and it doesn’t recognize anything on TELEM1 or 2. Swap the carrier board and the problem stays with the cube. This happens with the two IBs I was handed.
Well, no. The change notes are not accurate. PX4 does need an update to support this. Confirmed this with people working directly with Cubepilot. Ardupilot does support the IB.