I’ve been struggling with UEFI on my HP Probook 4540s laptop and I think I can provide valuable information on this issue.
When I first switched from BIOS to EFI, Fedora was the only distro that knew how to make my laptop load GRUB automatically.
Now most distros install grub in a fat32 partition mounted as /boot/efi, and the generated grubx64.efi is put in a folder. They also add entries to a small memory that holds the boot order (efibootmgr handles this), but strangely my laptop ignores these entries and only looks for /boot/efi/EFI/BOOT/BOOTX64.EFI.
If I have Fedora installed and I install openSUSE, it will only create /boot/efi/EFI/opensuse/grubx64.efi, but my laptop will still load Fedora’s GRUB because openSUSE didn’t overwrite /BOOT/BOOTX64.EFI.
I can manually boot any EFI file, including from other mediums like CDs and USB drives, but if BOOTX64.EFI is not present, I’ll get an error that no image was found.
Back to Antergos, at this point I cannot boot from a dd-written USB drive, although I can see the EFI files there.