Okay, further data. I found that if I switch to the second camera (the one on the screen) and then flip back, the camera appears to work. That leads me to think it's some form of software, not hardware issue.
Motorola Droid Maxx XT1080, non-DE, but unlocked all the same!
Nexus 7 (16gb) stock rooted 4.4.2
"The goal of terrorism is to terrorize us: to make us afraid, and make our government do exactly what the TSA is doing. When we react out of fear, the terrorists succeed even when their plots fail. But if we carry on as before, the terrorists fail -- even when their plots succeed." ~ Bruce Schneier