As described in the title, if you are standing inside a trapdoor, sneaking won't work.

What I expected to happen was:
Player will sneak as normal when inside a trapdoor

What actually happened was:
Player model height won't change, but seems like nametag above the player head will be hidden from others when preforming this bug on a server

Steps to Reproduce:
1. Standing at the predicted trapdoor position
2. Right click on the trapdoor to change its position so it's inside the player
3. Press sneak button and it won't do anything

Screenshot description:

1.png: sneaking is normal when standing beside the trapdoor

2.png: sneaking is normal when standing on top of the trapdoor

3.png: sneaking is abnormal when inside a horizontal trapdoor

4.png: sneaking is abnormal when inside a vertical trapdoor