Resetting the DJM-V10 can help eliminate many glitches and problems, here is how to do it : 

1. Turn off the mixer.
2. Press and hold the [MIDI START/STOP (WAKE UP)] button.
3. Turn on the mixer (power button) while holding this button.
4.  The [FACTORY RESET] screen appears.
5.  Use the [TIME] knob (Beat FX section) to select YES.
6. Confirm with OK (touchscreen).
7. Turn off the mixer to complete the reset.