In the _JAZZBOP.STY on a standard tune like Cherokee, the first chorus is as expected, playing in two for the A section, and in 4 as the bass walks in the B section. The middle choruses SHOULD be all bass walking and drums in 4. The drums do move to the sticks and play in 4 MOST of the time, but on the 4th chorus the drums switch randomly to brushes.

This has happened on other tunes as well but I am sending this example to support. So right in the middle of the soloing choruses the drums drop back to brushes for a few bars and the momentum just drops off entirely.