I’m not familiar with the brand, but general ideas that come to mind to troubleshoot are:
- Disable secureboot if enabled. Understanding you’ll lose that security feature of course.
- See if there’s an option to mark your storage as removable in the installer (–removable flag in grub iirc). My (pretty old) motherboard does not seem to respect attempts to add uefi entities but it happily boots off a “removable” uefi install.
Some suggestions for solid state alternatives as old mechanical magnetic storage has such a high failure rate. But retro whatever way you want, of course!
You can get ide to compact flash or ide to sata adapters and get some reasonably modern solid state hard drive storage in there, if that interests you. I understand (haven’t tried personally) that compatibility can be kind of a crapshoot though.
You can also get a gotek which has a floppy interface and can load floppy images from a USB thumbdrive. Which might be a more functional option than getting a USB floppy drive for a modern machine.