I had to go back and re-apply for my personal certificate and then go through the whole chain again for it to work. Had to revoke all of my profiles and certificates on the site (after re-getting my personal cert), remove all copies from my local machine and devices, and (with several reboots between "installs") got it working again. Took about four hours, give or take.

My developer was having the same problem and we thought it must have to do something with the code. Thanks for posting this.