Same here with a GR IV, missing from Lightroom CC but camera presets are present in Lightroom Classic. I tried uninstalling LR CC but the problem persists.
Same issue here! My GRIIIx camera matching profiles is missing from my iPhone and iPad, but present on my Mac. Tried deteting the app and reinstall, and also what Tabitha recommended (keeping the app on for several hours) but to no avail.
If anyone else has this issue, it did resolve for me. I waited a few hours with Lightroom mobile running and now the camera matching profiles are there!
We've reviewed your report and are able to see profiles for the Ricoh GRIIIX profiles. Can you select a raw file/dng file again and confirm that the profile does not appear.