Crossfader transformer

Hi I am using DJay Pro 2 on iPad Pro and have been experiencing an issue with the crossfade. When I am scratching I set the fader to the opposite deck and tap the fader to cut in the sound, transformer-style. For example scratching on the left deck, I would have the fader in the full right position, then tap on the left of the fader to cut in the sound. The fader switches to the middle position for as long as my finger is on it, and then back to the right when I remove it.
This works fine for a while, but usually after a few minutes the fader doesnt do this any more - it stops in the middle, rather than flicking back to the right, and the seems to revert to the slow, soft type fade usually used for mixing. The only way I can get it to return to the cut mode is to completely exit the app (ie the double-tap home button and swipe up) and then re-open it.
Ive tried the ‘cutting mode’ option on and off in Preferences plus various other things but no success. (Incidentally none of the crossfade options - cutting mode, invert or jog pitch seem to do anything at all anyway!).
Anyone had the same experience, or got any ideas how to resolve it? Thanks