In RB
First, maybe try the Make All BB tracks regular tracks option (right-click - Track option)
When they change, they will not have Blue track names anymore, if they did.
Then it behaves like RB instead of BiaB. Some RB functions only happen on regular RB tracks, as I mentioned; the Blue BiaB tracks continue to try to emulate a more BiaB behavior.

If you opened a BiaB file in RB, the tracks may be acting like BiaB tracks and not as expected like with other RB files.
After changing them to regular tracks, use Save As (to a SEQ file format) to preserve your original BiaB file.
Then work with the resulting SEQ file in RB.

After that, how exactly are you loading the plugin?
I'd normally right click the track and assign to a different VSTi port, then assign the desired synth to that port in the resulting popup.

Make your sound your own!
.. I do not work here, but the benefits are still awesome