Hi Mark,
i had the same problem. I finding it:
1. IP45/46 pressed button MIX, fader set to 0
2. Aux1 fader set to 0, from Aux1 nothing signal
3. Aux2 fader set to 0, signal OK, sound fine
I test all, copy aux2 to aux1, … nothing.
than i random pressed button MIX on aux1 and fader was on -40 (?), pressed button MIX on aux2 fader was on 0 (?). ??? I pressed again mix button on IP45/46 – fader on 0 and aux1 fader on 0, aux2 fader on 0. ???
i play with button mix on input IP45 and mix button on Aux1,2. It is not the same ?
then i control: mix button on aux1 to 0, fader on ip45/46 to 0. sound fine 🙂
jano