Official comment
@Tomasz > I just checked this with a couple of different MIDI devices and they all worked as expected; it sounds to me like your MIDI controller is either not issuing a temporary state change (0 > press > 255 > release > 0) upon release of the button, but rather toggling the mode (0 > press > 255 > release > 255 > press > 0 > release > 0).
The LPD8 has an editing software; check if you're able to reconfigure the button action modes.
