Thanks - though I sometimes have that button, and sometimes I don’t. Weird.
(So yes, I was missing the obvious…)
EDIT: It appears the sequence of what I plug in first matters. If I plug in the Kontrol X1 first and the Audio 10 second, I don’t get the mixer button. if Audio 10 first, then I get the button. Considering I have set up my gear on a hub so I only need to plug in one cable, it’s a bit of a gamble which device is detected first. But I can work around that.
It is - it doesn’t have an audio interface. It’s weird about midi though, for example, it doesn’t work on the iPad. Maybe that plays a role. Who knows - in the end, I now know where to look for the Mixer show/hide button, and if it doesn’t appear, I just unplug the X1, restart Djay Pro, and plug it back in. So no big deal.
That’s exactly what I was going to suggest @jimbobatzke. Perhaps your hub is also playing a part in this. If your Mac has enough USB ports, maybe try testing with direct connections.