Something blocking audio from being heard with VEP

Hey hey everyone. Happy '18.

Any VEP users out there?

I’ve used audio FX on a couple of tracks that route to an FX rack in Vienna Ensemble Pro. No audio can be heard.
Granted, I am almost at max. average peak load CPU-wise. Does Cubase just decide not to sound audio tracks that may take CPU over its limit?

Has anyone experienced something similar?

Then when I press stop after playing the project, I can hear the tail-end of the sound that I was expecting to sound during playback.

Help would be much appreciated.

I should add the meters are all displaying with activity even though there is no sound on those tracks.

It is definitely a plugin in the VEP FX rack because when I remove the VEP audio insert the track plays.