For session locks, yes. We have yet to restore the leaderboards portion and are preferring to implement it differently to avoid risking this problem again.
We wrapped our MemoryStore API calls through pcall and it would return errors simply as “Internal Error: Internal error” more frequently than we saw reported on Roblox’s analytics. This would happen in small bursts, like we would suddenly see multiple failures come in at once every 3-15 minutes. This was consistent.
The API call was simply an UpdateAsync that stored a string representing which server the player was in with an expiration time of around 60 seconds, re-applying every 45 seconds the player was in the server.