it seems to be a strange metering issue involving the insert slots. and of course only became apparent because of the limiter in my LR chain.
if insertA of mainLR is deactivated, levels on metersMTX match levels on metersLR (MTX having dyn8 fully activated on insertA)
if insertA of mainLR is activated and MTX having dyn8 fully activated on its insertA, levels on MTX meters still show pre insertA Metering levels of mainLR.
if insertA of mainLR is activated and dyn8 of MTX has all bands of multibd4 deactivated, levels of meterMTX match levels of meterLR.
I have sent all information to A&H support.