This could be a world setting issue. If you go to general in the world settings there is an only allow trusted skins. Switching that should help fix it.
Do the other players have the "Only Allow Trusted Skins" option enabled in Settings > General? If so, are they able to see your skin if they disable this option and rejoin the world?
This could be a world setting issue. If you go to general in the world settings there is an only allow trusted skins. Switching that should help fix it.