Problem: Boot Camp Control panel on Windows 10 doesn’t display macOS drive/partition which you could select to boot into.
Cause: The Boot Camp utility is not able to read APFS drive/partitions. The most recent Boot Camp version is currently available only for iMacPro1,1.
Solution: Basically you need to update to Boot Camp 6.1 or later.
brigadier.exe --model iMacPro1,1
and run the Boot Camp installer manually:
msiexec /i BootCamp-041-55643\BootCamp\Drivers\Apple\BootCamp.msi