The last install I had before installing Solus was Makulu. I press F12 to get boot options, select the UEFI Boot disk, and it just fell straight back to loading Makulu. Now having installed Solus in legacy mode, If I try and load the UEFI USB I get
Invalid Image
Failed to read header: Unsupported
Failed To Load image: Unsupported
start_image () returned Unsupported
I always use Gnome Disks as its part of the Gnome Environment, which is my preferred desktop environment, and I've never had an issue with it. Because of recommendations on here I tried Rufus, as an AppImage on Fedora, which produces the same result as Gnome Disks. I then tried Ventoy which throws out all sorts of BIOS and Firmware errors, see my above (Post 24 I think it is) which is why I looked to see if there was an update for my BIOS.
If it is a BIOS issue it would be interesting to know what requirement that the Solus USB stick needs which is different to every other Linux distro I've tried.
If I can summon up the enthusiasm, I'll install windows and update the BIOS at some point today.