Sometimes there happens an issue with simultaneous touches when you can't touch more than 2-3 buttons at the same time. For example, when you press a few pads at once, the sound is not reproduced from all pads, but only from some of them. The main reasons for such behaviour could be:
1) your device does not support as many simultaneous touches. Please pay attention to the number of touches depends on the device. (If a device supports a maximum two touches, then only 2 touches will be available in the application).
2) the pressed pads are in the same group. (To avoid a problem with a sound please use the pads from different groups)
3) setting for support specific gestures is turned on on the device. (We know one lifehack with HTC device: if you have HTC then you can try to disable ‘HTC gestures’ in the device settings and Multitouch will work properly.)
4) Also please try to use app MultiTouchTester - https://play.google.com/store/apps/details?id=com.the511plus.MultiTouchTester to view if your multitouch works as expected.
5) And please disable the option "Use 3 fingers to take screenshot" in the settings, gestures menu.