rpmurray
There could be many reasons why you’re having there issues with your A&H, a faulty one for starters. Can happen.
Bad or not so great quality cables and or Camera Kit adapter.
Insufficient power to your iPad. Too much power to your iPad.
Another app running in the background like a DMX app (happens to me occasionally with Photon 2).
Electricity issues in the venue. Etc etc.
The UI24 however is documented many times with these USB issues, and so while I appreciate your input and am sympathetic to your issue, the two mixers share very little in common when it comes to operating as an interface. Trust me 😊.
Besides the occasional DMX app causing a playback error as it crashes there is zero issues for me, and a number of my friends running the same setup with the QU-SB. Zero. If I were in your area I bet I could quickly identify your issue, being the actual mixer (doubtful but it can happen) but more likely another reason. Usually something small and silly. My confidence comes from experience however i will not claim to never be wrong. This happens enough times for me to admit that there are enough exceptions to the rule, however the QU is a robust mixer, USB wise at least.
I’d like a full rundown of your setup from the iPad (and its version) down to the cables, adapter, USB hub should you use one, power supply for your iPad, and type of USB cable from the iPad to your mixer. I found that that cable alone can cause major headaches, I have invested so much money in buying special “audio specific’ usb cables (dumb idea but good to experiment) to the simplest cable (also dumb), but usually something that comes with a decent audio interface would work well enough.
Anything above 2m or longer is prone to problems. Avoid those. If you’re using a hub, there are “special ones” that are proven to work with audio and only use active USB over Ethernet (I could link to the one I got) with a CAT6 or 5e and also don’t exceed the recommended length.