Newbie user here

I've flashed the bootloader and installed firmware to my Gotek drive. The drive is in Indexed mode with the relevant config file copied to the USB stick, so far so good.
The A3000 sees the drive, and I've formatted a "disk" from the Acorn and that works great. I'm having trouble using disk images though, I'm sure I've missed something simple!
I've converted the ADF files to HFE and named them appropriately, the Gotek can see them and I can change the disk using the buttons fine, but of all the files I've tried I get a "Broken Directory" message when trying to access the drive. I'm fairly sure the ADF files are ok as I wrote them to a physical floppy and tested them first.
Has anyone got any pointers on things I should check?
Many thanks,
Dean