SOLVED: So the boot order was correct in UEFI, but for some reason CSM was disabled. Re-enabling that now causes GRUB to appear, and the PC boots into Linux without any other input. Thanks everyone!

Not 100%, but I’m not a BIOS/GRUB expert. When I restart my computer my options are currently either do nothing and let it automatically boot to Win10, or go to BIOS and manually select Linux. Manually selecting Linux takes me to the GRUB screen, which doesn’t appear at all when the computer boots to Win10. Does that information help?