Hi, When I cook beef sous vide it usually comes out smelling something like dogfood. But after searing in butter, it is excellent, and smells good.
However, recently I cooked a 7 bone chuck roast for more than a day. I set the temp to 54 C, I usually use 55 C, but wanted something nice and rare. It smelled disgusting!! Even after washing, I couldn't eat it. It was an unfamiliar smell, very strong, not plastic. I can only think some bacteria went wild in there. I wonder what it was.
I didn't wash the meat before hand.
Next time I washed the meat carefully and dropped it in boiling water briefly. I bumped up the temp to 55.
That one smelled OK after sous vide.
Good Luck !