I was lucky enough to land some artifice gauntlets form the master dungeon, however I have attempted to run unstoppable sidearm, overload bow and unstoppable fusion in the 5th slot. But only my unstoppable sidearm and bow worm. Linear fusion does not. Attempted this with barrier and sidearm along with bow. Still does not show third champion mod in service. Is this by design? Or is this a bug/error. I cannot find much online to support this.