Rick’s (Rixter above) solution did NOT work for me on an old SanDisk Cruzer Glide 8GB. This USB Drive still shows up as a Local Disk in Windows 10 and does not show up in UNetBootin to create a USB bootable version of PartedMagic. This occurs even after setting the Boot Flag property with GParted.
A different SanDisk Cruzer 16GB shows up as a USB Drive and works fine with UNetBootin.