The arms of players that are crawling or swimming are sometimes positioned differently for other players

The Bug:

The arms of players that are crawling or swimming are sometimes positioned differently for other players.

Steps to Reproduce:

1. Build the setup as shown in the attachment below. setup.png
2. Get two players and label them "Player A" and "Player B".
3. Get "Player A" to stand on top of the diamond block facing the setup.
4. Get "Player B" to begin crawling using the trapdoor.
5. Get both players to take note of the arm positions of "Player B".
6. Take note as to whether or not the arms of players that are crawling or swimming are sometimes positioned differently for other players.

Observed Behavior:

The arms of players that are crawling or swimming are sometimes positioned differently for other players.

Expected Behavior:

The arms of players that are crawling or swimming would not sometimes be positioned differently for other players.