I downloaded Strava with one intention. To beat my brothers time to hike up Ben Nevis. I Paid the annual subscription and I drove to Scotland. My brother and I had walked up a few weeks before that and ranked 5th fastest without really pushing. So we decided to come back and try again, but this time we would walk our own walk and see who could go up fastest. I beat my brother and was sat waiting for him at the top for 3 minutes. Somehow, Strava did not record it. It clearly shows my route and the time, but doesn't match it up to other people. I followed the same path as my brother and I had walked last time. My brother followed the same path as me (only a few minutes behind) and he was recognised! I don't know why this has not worked but its very annoying. I am not walking up again to prove my point, its a 6 hour drive away. If I bought a smartwatch just for that walk and it didn't work, I could get a refund. This is a simple consumer rights issue.
@NickIrvine - If you post a link to your activity, and maybe the one for your brother to compare to, we could look at it and see if there is something obvious that happened. There are a number of potential issues. One, you could have had issues with "GSP drift", where the tracking of your device was offset somewhat from the actual route and it didn't match up correctly with the segment in the file. Another potential is the start and end points could have been such that your activity missed it by just a little bit and thus didn't match correctly. You could also use the "submit a request" from the bottom of the activity feed page or support pages to have the Strava technicians take a look at why the activity didn't match up correctly.
One other question, are you sure you marked the activity as the correct activity type? i.e. walk vs hike vs run? If it is listed as a run, it won't show up on the hike segment leaderboard and vice-versa.