NMLGugers, I have shifted to the commandline for this, though I will propagate Ubuntu versions with the supplied GUI application. My most recent trial of other OS's was to make some MX usb's thus:

 sudo dd bs=4M if=MX-19.x_x64_copy.iso of=/dev/sdb

which is sudo dd bs=4M if=TheISOofChoice of=/dev/YourUsb; run this from whichever folder the File.iso resides in.

I let the ISO file reside in "Downloads" and use the terminal to navigate there and proceed with 'dd' and use 'sudo' privileges as the access to the /dev/sdb requires root privileges. It takes a bit of practice and patience. Practice to follow a preferred variation of the 'dd' syntax and patience to let the process finish - it may take 8-10 minutes for it to complete while it seems to hang. 'top' may indicate a "D" for uninterruptible sleep, but it will finish out, just wait. I encourage everybody to have a method to create install usb's and  share them with friends.

By the way, MX was recommended by the ABQLUG and is an interesting variant GnuLinux.

Practice on this is worth the effort and dd is always in your GnuLinux system.

Thank you, Ted P