I am also having the same issue, my input 1 also sends to aux 1 even when muted. I have tried finding the ‘Mix Ext In’ mentioned but to no avail. It would be lovely if anyone can walk me through the steps to find it. Note: I am also on the SQ-7
What pick off point do you have selected for aux 1?
What are you using aux 1 for, stage monitors, live streams ect.?