Cortex boss bugged

I left cortex to do a trade, came back and there is no boss. My maven didn't witness and no loot dropped.

Edit: Apparantly when bosses die while you are not in an instance you lose all the loot and the boss vanshies. Note, don't leave your boss fights for trades, you lose everything. Working as intended.

Thank you for the quick answer GGG. I learned something new today