I just got my new Behringer FCA1616 unit working and wanted to check if this issue is on MC's side:
Version: 19.0.125 (also previous)
Setup: 2.1 channels / with/without "only mix to 2.1" checked
JRSS Subwoofer / with/without Subclarity
Symptom: When adjusting PreAmp level in the Equalizer, the sub output level remains constant, only Left/Right output are affected.