Gio as I have stated before here and the other forum the current state of the X-Air leaves only four out of the five control surfaces useful (Windows, Linux, Mac, Android, iPad). The iPad is the exclusion. When I toured the Music Group Canoga Park facility I remarked to Michael that I probably won't consider the unit ready for prime time until V2.1 of X-Air. I'm sticking to that. I use the iPad only for test not for any gigs. Against my better judgement I did use the XR18 for one gig controlled by a Android tablet with PC in tow. It worked flawlessly. At the present state of affairs the order of preference for me is PC (Android emulator is available for it as well) then a Android tablet. Forget the iPad until at least the next release. I'm currently putting together a battery operated system for my wife
that is using the XR12, CBT 50LA, and Sennheiser wireless, Yamaha keyboard and the essential water bottle holder. Still debating which amp to use leaning towards a iNuke 1000DSP. It all has to fit comfortably into the trunk of a car and of course be on wheels. Weight being the biggest problem for lifting in/out of trunk. A Choir Director's workstation that should be ready in about a week or two (custom cabinet).
The 2 second XR reset would have been my first go-to on your problem. Hope it's not a hosed XR18.