When you cannot find your run there are usually one of a few explanations:
1. Your Run May Not Be Your Highest Scoring Run
By default, your character profile page shows only your highest scoring runs. However, you can click an individual dungeon from the table to see all of your recorded runs for that dungeon:
2. Our Crawlers May Not Have Scanned Your Run Yet
Our Crawlers are continually scouring for newly completed Mythic Keystone runs. However, this is certainly not an instantaneous process, so if you have just recently completed a run you will need to first wait for Blizzard to show your run on their leaderboard (usually takes about 30 minutes to an hour), and then wait for our crawlers to detect the new run on those leaderboards. With the new Blizzard Character Mythic+ API, you can also scan your character directly to have your top runs tracked.