Apple Developer Certificate: Incorrect Team ID
After a back and forth with iOS Developer Help personnel, we've determined that: The Team ID for the Development Certificate is randomly assigned and will be different from the Distribution Certificate. The arbitrary Team ID for the Development Certificate ultimately has no bearing on reality. The code signing issues I was having were coincidental and were eventually fixed by (what you can read elsewhere on this site) revoking everything, re-issuing all certificates...and (what I was not doing) WAITING PATIENTLY (took about a day) before everything went back into effect.