No errors, flash drive never shows activity. With EFI Boot option I successfully booted up to the Debian start menu, but when I select the first option to start the live Debian, then nothing happens.If I plug the USB drive directly to the Mac, then an EFI Boot option appears as expected.
USB drive is USB 3.0 Sandisk Extreme 32 GB drive, formatted with OS X Disk Utility in FAT with GUID.
Live distro should have persistent storage and work directly from the USB flash drive. I need a working Linux (live) ditro, preferably Debian 9 or CentOS 7, that will show on MacMini (Late 2014) boot menu (holding the option/alt key).