My vote is #2 (We will address this issue as soon as possible). #1 doesn’t sound bad, I just feel like using “start” isn’t necessary because it is implied. 🌈 Nicky 🤗

Both sound fine. #2 is better because it is more concise. Your question could be written better as, "Which of the following sounds more natural?" or "Which sounds more natural?" or "Which expression is more natural-sounding?" or "Which is more natural?"