I ran across a style that had the same problems when using Coyote Forte DXi. Using Roland VSC/DXi the bass played fine. I ended up finding another style.

If you run across this, check the bass line notation (editable) and see if the notes overlap at that point. Odds are they are the same note and they overlap. If you must use that style, you can edit the bass line in the style to minimize the overlaps.

I assume some synths handle the overlapping notes better than other.

R