FL Studio 20 w/ Reaper slaved via Bidule

[bny2013]

I have FL Studio 20 and also have Bidule VST which allows me to run rewire apps (FL20 Mac doesnt have rewire yet)... but when I hit play Reaper's transport section flashes red. The play cursor moves but I get no audio if I have an audio clip on a track.

Oddly if I preview an audio clip in the Media List it plays fine. If a drag that audio file to a track the audio doesn't play.
Doesn't really make any sense.

I want to use Reaper in FL Studio slaved to make use of the Item FX... quite a nice feature.. but not able to get it to work.

Ableton and Reason run fine in the set-up, but not Reaper.