If you are in another app, and Dispatch is closed in the background, then you press the home button on the remote then quickly press right as Dispatch is loading up, the apps menu will be empty.

It's very easy to trigger this by mistake. This is on Shield Pro.

EDIT: Actually, it happens suddenly either way. Even if I wait a bit. Can this be because I have disabled the "Live Channels" app? I just did that recently because I didn't want it showing up in Dispatch and I think this issue started around that time.