IIRC, Android phones sometimes have ways to switch the USB modes from Mass storage, to camera like, to developer modes. I’m blanking on the exact terms, but remember that being an issue on my Samsung Galaxy ages back on my Mac and with some automated tests at a past job. For some reason I had to manually flip the USB mode to change between where iPhoto would see photos, and where I could see the music folder.

Maybe something similar is going on here between Windows and the S8? I think it was the pull down notification tray that offered the ability to switch USB modes on that old Galaxy.