I'm also getting something similar, like stuck notes or huge latency that comes in suddenly and unpredictably. I got the new Pianoteq iOS app and tried plugging the USB out from the Take5 directly into the iPad via the "camera kit" USB dongle. Quick fix for the problem is to unplug and plug in the USB cord from the back of the Take 5, and then it seems to work normally. All MIDI settings I can see in the global menu have been set very conservatively, like I've got local off, most everying else 'off' where applicable, just going for basic MIDI notes out over USB as much as I can. No MIDI echo or output controls in Pianoteq as far as I can tell.
I'm not familiar with the Pianoteq iOS app but assume that's the tone source and that the Take 5 is just being a controller? If so, then I wouldn't expect it to matter whether or not Local is set to on or off.
Do you have a way to accept the T5 DIN MIDI out to the Camera Kit input on the iOS device so at least you can break looping by not plugging in the T5's DIN MIDI in?
You should probably contact the app author if no one here has a solution. Good luck!
Thanks for the reply. Yes, I was using the Take5 just as a controller. I could also leave Local On, and go for a layered sound, or mute the T5 at the mixer, so yes, local shouldn't be relevant.
Think what you're suggesting is getting an inline usb/din mini converter cable, like the Mio 1x1. I've never had good luck with that kind of device. They create more problems than they solve, in my experience. If the problem persists after other troubleshooting I'll give that a try, leaving MIDI in on the T5 disconnected.
I've also noticed that I sometimes get similar MIDI glitches when using my main controller keyboard (Studiologic Numa Compact 2) over USB into my Mac mini running the Pianoteq desktop app/VST. I think I've pinned it down to the fact that the glitches tend to show up only when I 1) turn on the keyboard and then 2) start the software. If I 1) start the software and then 2) turn on the keyboard, it seems more stable.
I think it's just coming from the way the MacOS/iOS recognizes new devices appearing on the USB MIDI bus. I'll have to try the experiment with iOS as well, only plugging in the USB MIDI connection _after_ I've started up the app.