I have recently applied the mod swift charge, which has a secondary perk called Pulse Rifle Scavenger. The secondary perk will only proc when an arc mod is installed into the same armor or another arc charged with light mod is applied to another equipped armor piece. I have installed this mod into the gloves of the hezen lords warlock gauntlets from the Vault of Glass raid. On these gauntlets I have also applied the arc mod superstructure striker, a mod specific to Vault of Glass. This is an arc mod equipped onto the same armor piece as swift charge and should proc the secondary perk; however, this does not happen in game. I also tested if it would proc if I entered the Vault of Glass raid since the arc mod I had equipped wasn't active in orbit. But even after entering the raid and activating superstructure striker the secondary perk was still not active. I believe this bug may exist for similar combinations of mods such as the other arc raid mods or any of the arc mods with secondary perks; however, only the specific case above had been tested and confirmed.
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Check and see if it works with mods that give extra stats, just equip that and the raid mod and see if it will give extra stats.