It was able to load the system from USB drive no problem, so I formatting a disk so I could save to it. (I made a few other copies of the system disk on the USB drive)
It seemed to get about halfway done and the show "FILE OPERATION ERROR".
This is the error I would get when a disk was corrupted while I had the original floppy drive in there. it meant that disk was no good and had to be tossed.
i'm trying with other USB sticks, but no luck yet.
I've been able to load instruments from files made from floppy images, but I haven't been able to try saving since they're all full. the OS disk has a little free space, so i could try recording & saving a short sample on that.
I only have the "M0" jumper set on the GOTEK.
It seems to be the same problem in this thread. i guess i need to make an image from a blank formatted floppy?
https://hxc2001.com/floppy/forum/viewtopic.php?f=17&t=749

Note : none of my USB 3.0 drives are detected by the Gotek. the screen just says "Hxc" and USB drive's activity LED blinks constantly.