If you look at EZKeys/EZDrummer
if the Sync to Host button is on and you hit play in Reaper it will play EZKeys in sync to Reaper,
if you hit play in EZKeys it will play the track from it's cursor position in EZkeys with Reaper stopped.

In the pic each track has a play active button
if I hit play in Reaper it will play those tracks back in sync to Reaper
if I hit the main play button in the BiabVst plugin it will play those tracks back with Reaper stopped (from the selected bar in the chord sheet is needed rather than from the very start of the file)
to do that now I have to go in and out of Preferences to change Sync playback.
So Bass Drums Piano are selected to play.

Full Screen

What also needs fixing is if you click on a track name button and your mouse moves slightly it will drop the track into the DAW.
The drag and drop should only work when clicking the audio or midi icon after the track name button.