Fenerax's Joystick problem

I am using the joystick featured in endless youtube tutorials about mobile development but my joystick is sticking on mobile device from time to time and doesn't reset when releasing the finger. Don't know how and when seems like it's doing it more or less randomly. Sometimes it seems because I hold two sticks, but I am not sure. Unity answers didn't help much, I didn't have to lock or unlock the fixed joystick(most answers featured those solutions).