Hello. I upgrated from traktoe 3 pro to 4 pro only because of steam files, and now i don't have that option, only on track that is originally already in software collection
Just add your tracks to a playlist, then enter the playlist and generate stems from there.
All is stated HERE among the update listings.
Ya, I think you have to do it in a playlist. Seems like a bit of an oversight, but I had the same problem and found a youtube video where they guy mentioned it.
I just linked to the post that lists this behavior, to be fixed at a later date. Check it out for the complete list of reported bugs.