Using Cakewalk at least one mixer fader jumps down once I hit play.

This is a behaviour apparently caused by MIDI files which are exported either from Guitar Pro or Tux Guitar. These programs seem to add weird automation data to the MIDI file which affects drum plugins in the DAW Cakewalk. Not only MTPDK is affected by this.

A quick solution was provided by Cakewalk once we reached out to them. Watch the video above to see how it works:

If the option "Event List" isn't available for you, change your "Workspace" in the top right dropdown menu of the Cakewalk window to "None" or "Advanced".