Thanks, a lot. I finally got this to work after adding a "/boot" directory after the efi one and adding the renamed bootx64.efi (formely grubx64.efi).
Along with Jesus you are my friend.
Very recently someone had a similar problem :
https://forum.artixlinux.org/index.php/topic,5788.0.html
https://forum.artixlinux.org/index.php/topic,5788.msg36214.html#msg36214
Also like the last thread the solution makes no sense according to the provided info but glad it's fixed, Jesus clearly does good work with computer issues.