Upgraded from 8.55 and the app starts fine for me on Q2, regardless of whether tracking is enabled or disabled.
Yar The 'drag video' control is really broken in this version. When I press the button combo to activate drag mode, the view jumps (i.e. the virtual camera rotates) without me doing any dragging. If I press and release the button combo several times, without dragging, the view jumps a bit each time and then the video is upside down.