Originally posted by Limdood:

that is a bug/feature of the mod. If you die with a full inventory and those added armor slots full, then your armor is deleted. I have the mod as well and its happened to me a few times. I just chalk it up as the price for having a few extra slots. I try to be careful not to fill my inventory, especially in dangerous areas due to that.

Not a game issue, a mod issue. report it to the makers of the mod

They have an updated version that fixes it. It does not come up as an available update in Vortex.