tarsan［たーさん］
VRChat SDK Base, Worlds 3.7.6
This can be confirmed on the LeaderBoard in Example Central.
  1. Open the LeaderBoard Scene in Example Central without editing it, and run Build & Test with three or more Clients.
  2. Jump and check. The client data of the instance master will not be synced to other players.
This case may not occur. When I checked, it was successfully synced about once in ten times.
I also made a leaderboard that used user data with a minimal, but similarly the client data of the instance master did not sync.
(I noticed this case when I wanted to create a simple leaderboard, focusing on the User data feature that allows you to get other players' data.)