Ignition randomly fails to launch full screen

We have a panel computer with Ignition Onboard, running on Linux. It is configured to automatically log in and launch the Perspective HMI in Kiosk Mode. This works just fine 80% of the time, but the HMI will randomly launch at the correct width and a quarter-inch of desktop showing, or the window will be really small and scrunched into the corner of the screen.

Any ideas what could cause this?