Absolutely yes. You need a common ground for some systems like the BIM to work.
All vehicles have the ground tied to the chassis frame. On my 2021 Axis 24.1 (same coach as yours) there is a single cable coming from the negative terminal of the house batteries that goes to a stud on the frame. Some individual grounds come off of that stud like the cable to the converter. But some like the generator use the frame for their ground connection.
If you are having charging problems and I had them on my new Axis, there might be two sources:
The chassis alternator didn't seem to charge correctly. I investigated and found that Thor routinely wires the Precision Circuits BIM 160 incorrectly. The chassis alternator should be wired to the A terminal. Thor wires it backwards. I corrected it and all of my chassis alternator charging problems went away.
The other may be the WFCO charger part of their converter. Despite their literature saying it is a three step charger, my experience tells me that it is a single fixed voltage output charger, set at about 13.5 volts. This means you get very little charging until the house batteries are well discharged.
I replaced it with a Progressive Dynamics 9260CV and it now charges great.
So definitely rewire the BIM. It is easy to do, just make sure none of the cables touch each other while you do it. The PD charger change out was a little more tedious as it is not a drop in replacement, but I made it work.