Why did my FM transmitter mysteriously die?
The problem ended up being very simple. I followed a schematic/tutorial for the FM transmitter module online. One thing they tutorial left out is that the LA pin must be held either high or low. It selects the i2c address. So, what was happening was the module was randomly changing i2c address during operation. This lead to all of the problems I had. Now, I tie it to ground, and everything works great