msOS will always show the GPUs that are detected by the driver - so if driver isn't detecting GPU, then msOS won't detect them either. You can do several different checks to improve detection.
First and foremost, create and check diagnostic report, which will show you if you have booted in UEFI and if you have internal GPU disabled. Then check if you are running viable msOS version for your mining setup. You can find all msOS versions and compatibility instructions in our archive.
Next, check if your rig applies for any of the following points:
pci-realloc
nvidia-update
command as explained here.If nothing of these settings fix your issues, double check risers, cables, and connections as these are usually the reason why GPU isn't getting detected.