External effects routing

I’ve got a couple of external effects - Eventide H3000 and Lexicon Pcm80 that I’m trying to use. I’ve got them setup as external effects (via vst connections), then as FX channels. Tracks have the external FX channel as their output and the FX channels have the main stereo out buss as their output.

Mixdown is in realtime and I can hear the external fx being played - but when I listen back to the mix the tracks with the external fx are at a different level than when monitored. What am I doing wrong?

One thing I’ve noticed is that if during monitoring I pull down the fader for the main stereo buss the tracks with the external fx don’t reduce in volume? I’d have thought they would because the fx channels are routed to the main stereo buss?

Driving me mad and probably something really simple that I’m overlooking.