The Lumix GH7 and Lumix S1M2 are some of the first mirrorless cameras to record ProRes RAW internally. Going from past experience with other cameras and Atomos recorders, the entire configuration is very sensitive to the exact firmware version on the camera, recorder and version of FCP.
Some of those cases involved a multi-stage firmware update on both camera and Atomos recorder before full RAW adjustment capability existed in FCP.
There were several cases where a certain Atomos recorder on a certain firmware version would record ProRes RAW from a certain camera on a certain firmware version, and FCP would import that, but some RAW adjustments might not work until camera or recorder firmware was updated.
In one case (Shogun 7) recorder development was orphaned, and while it could record ProRes RAW, it was never possible to make white balance adjustments in FCP.
Internal recording at least eliminates the external recorder config issue. However to examine your problem we will need:
(1) Your camera firmware version. If you have not tried this on the latest camera firmware version, update that and try again.
(2) A ProRes RAW sample clip from each camera to examine
You can upload the ProRes RAW clips to a file-sharing service and post the link here.