Issue resolved in WIFIPLUG 9.0+. This article only applies to WIFIPLUG 8.1.1 and below.
If you find that the WIFIPLUG app is closing almost immediately after starting it then you may have developed a corrupt cache and the app is having trouble loading it. To resolve this issue open your phone's Settings > Apps > WIFIPLUG > Storage > Clear Data.
Completing the above will log you out of the app and clear your favourite devices as well as your device-stored settings but will allow you to continue using the app.