Where do my replays appear after I share them?
Like Friendly Challenges, Replay Sharing will be visible in Alliance Chat. You will be unable to share your replay if you are not currently in an Alliance.

Why can’t I share replays right after I’ve updated the game?
After every update, older attack and defense logs can miss certain information, like new or updated units and buildings, which preventing them from being shared. You can read more about what happens in these cases here.

Why isn’t there a share button for my World War replay?
That’s because World War replays are already visible (if enabled) to members of your Alliance and the Alliance you’re battling!