After some testing I found out that origins that are not the standard ones, that are listed in a second layer, will make every player unkillable (Even with commands). They do not have to use the origin at all for this to occur.
The Origins themselves work, but this issue is game breaking.
I hope you will be able to find a fix soon ^^"

A little correction:
This ONLY happens if the Empty slot is selected when other origins are present in the second layer's list

Having an empty origin in any layer makes you invicible.
There is a bug currently that makes it true even if there is no eligible option to the player.