This is working for us now and ended up not being a connector issue. The user that the device was being provisioned for wasn't in a group that automatically enrolled into Intune (another team had messed up the prerequisites), so the device was being told by the Autopilot profile to do a domain join but could never apply the domain join policy because it wasn't ever getting to a point where it would receive that policy. The symptoms are the client stuck on "Please wait while we setup your device" and nothing happening.
In order to diagnose this I ended up targeting a Entra Join Autopilot profile to the device and when it completed the build and came out the other side with none of the applications installed and no attention being paid to things like Windows Hello policy I realised there was a bigger problem.
This is unlikely to help you if the only change you're making is shifting between the old and new connectors.