Since the upgrade to firmware 16, I can no longer tune lower than 20 meters to listen, QMX reverts to 14.074 regardless if CAT control or stand alone. I was using HDSDR to listen to other 30 and 40 meters ham bands and can no longer do this.
I don't think QMX is capable of doing this by itself, not as far as I know. The firmware upgrade would have done a configuration reset implicitly. Are you sure you hadn't made some edits in the band configuration menu which you've long forgotten? I'm assuming yours is a high-band QMX. So maybe it's as simple as reducing the lower frequency limit of the 20m band column in the band configuration screen?