jiquani's machinerium vaal altar stole my friend's gear

I was playing co-op with my friend and when we reached the vaal altar in jiquani's machinerium we were both doing the vaaling at the same time.

I think I vaaled my item first, which caused the altar to sunk down, stealing my friend's item on the way that he had placed. he also hit the vaal button but instead of getting his item back vaaled the UI just disappeared and he lost his main weapon he tried to vaal.

His item we shared on our party chat before we vaaled them.

this loss was pretty big for him so he is threatening to quit the game.

so far we have tried relogging, splitting the party and portalling in/out but we have not gotten his item back.

after relogging and trying a new instance the item is still gone for him and the vaaling process was also consumed for him (the vaal altar remains down for him).

He quit the game.