Heres the setup:
Mono audio track
External FX insert
Audio Connections setup for mono fx send and return on same channel (out on 5, in on 5)
Insert sending to Antelope Discrete 4 Control panel for DSP FX
Audio gets to Antelope control lan, and the the audio hits the FX, but the mono only sounds from the left-side and from the mono interface input channel 1. Not the send return. There is no active metering back in Cubase for this channel unless the insert is bypassed.
Cubase 10 Pro, Windows 10, Antelope Audio Discrete 4 SC