I wonder if the score not appearing is related to bypassing the ending forced reincarnation, and it trying and failing to upload a second score for the same run.
In that case, you could try manually reincarnating. It should try to upload the score again. You don’t have to fully reincarnate, the upload happens on the end screen before the leaderboard loads.
Oh, that's what I did, and before I even posted the message with my score. I even fully reincarnated, but I did notice there was a strange disparity between the orange number on the leaderboards and the score presented at the centre of screen.