Yes, I have dual HereV2 units running via UAVCAN on one of my builds.
Some things to check:
Do you have a terminator somewhere near the end of the daisy chain? Things work without terminators (or badly placed ones) until you get a long transmission line or a lot of nodes (from my experience).
Have you manually set a Node ID on the GPS? Most versions of the ArduPilot code do not yet support Automatic Node allocation.
Double checked your GPS_TYPE parameter?
If you don’t have a Zubax Babel to check it, what kind of readout do you see when using Mission Planner with AP in SLCAN mode?