Nowadays, we can put bison behind concrete and steel fences that they can't jump over, chase them with trucks when they try to run, and tranquilize them when they get unruly. This helps overcome some of their behavioral problems that stand in the way of domestication: their habit of migrating very far distances very fast, of jumping over any obstacle used to contain them, and their habit of splitting into sex segregated herds.
Without access to modern technology, the effort to domesticate bison just isn't worth it for stone age farmers. You'd have to have some major changes to the bison's behavior to make it worth the effort of domesticating.