Steps to Reproduce:

1. Create a new world with the "Multiplayer Game" and "Visible to LAN Players" options enabled
2. Build a platform out of transparent blocks (glass, ice, glowstone, etc.) in the air
3. Place a boat/minecart on the platform
4. Use a second device with a different Microsoft account to join the world
5. Enter the boat/minecart on Device 2
6. Leave the world on Device 2
7. Break the boat/minecart on Device 1
8. Rejoin the world on Device 2

Observed Results:
The player falls through the platform.

Expected Results:
The player should stay on the platform.

Video:
Minecraft 2021-12-31 15-53-31.mp4