If your High Sierra partition is APFS, then your Mac's behaviour is normal.
There is no driver in Windows to read APFS yet. Apple didn't update the Bootcamp software to that level. Therefore, the Bootcamp control panel cannot display any APFS boot partition. Same reason, that "reboot back to OSX" won't work either.
Apple recommended work around is to use Boot Manager (hold Alt during boot) to go back to MacOS. But if you a more "software" solution, Bootchamp with SIP disable also work (but you need to keep SIP disabled).
Other work around will be like stay at HFS+ (even with SSD, you can clone the OS to another partition, re-format it back to HFS+, and then clone it back). Or install an extra HFS+ 10.12.6 (or onward) to make bootcamp panel able to boot back to MacOS, and then further choose your APFS High Sierra partition inside that MacOS as the next startup disk. But in general, no one prefer this kind of "work around".