The camera is fine, but I'm now getting the continuous tone of dead rear sensors as I reverse. Anyone else?

 

I had one rear sensor die (passenger side) and had the same symptoms as you, but only on that specific sensor. The others worked as normal. The faulty sensor was replaced under warranty and it's been fine ever since. If all yours are firing all the time your issue may well be with the control module.

 

Apparently working normally today. Hmm...

 

That conforms to the "Uniform Code for Electronic Sensors, Guideline #34."