I guess I forgot to post my update to this. I thought I had narrowed down some logical reason for this, based on talking to the users who did and did not experience this phenomenon.

Based on the information I had gathered, it looked like those devices with 4.2 OS whose users had changed the theme to something other than one of the default themes loaded by the provider had this issue. Every single person with an issue had downloaded and set a new theme.

I tested with 4 devices at once and set them all differently. Two with new themes installed and two with a default. All were modified differently.

Alas, after all of that setup, none of the devices reset. I have no idea what the cause could have possibly been. We've finished our migrations, so I cannot try anything more and only a handful actually reported anything to our Helpdesk.