The contract doesn't mention anything about releasing multi-track raw files or releasing stems. If they want my time, they will pay for it, if they don't pay for it, they don't get it. Not a difficult concept, but one they fail to grasp.
So what's the problem? I mean if they don't wanna understand that you need to be paid to work - just like everyone else - that's their problem so let them burn in hell! Ahahah! If they REALLY need these raw tracks, they'll pay.
I personally never give PT sessions or processed tracks, that's MY shit. If the band wants the separate raw tracks or needs some processed ones for their gigs, they pay the extra time. But I try to discuss this kind of stuff before starting the project, then it can be written on the contract.