I had issues with UEFI booting on my PC, as I am using an SSD, an HDD, and an external HDD all containing several Linux installations, and GRUB was not helping. Finally, I could solve the problem by installing REFIND. Now I do not have to change the boot order in the UEFI bios to allow a specific distro to boot, as REFIND takes care.
On my old laptop, I could not install REFIND, as it does not support UEFI. I have an SSD with Siduction and Antergos installed. Although the GRUB list in Siduction showed Antergos, it would lead to kernel panic every time I selected Antergos for booting up. On comparing with REFIND boot entries, I found that Siduction was pointing to intel-ucode.img, while the correct img for Antergos was initramfs-linux.img, located in the Antergo boot folder.
I have now deleted the intel-ucode.img and made a copy of initramfs-linux.img, and renamed that to intel-ucode.img. Now, Antergos boots up fine from Siduction Grub. Only problem, I have to repeat the renaming of the img files every time Antergos has a kernel update.