After dying and going to main menu, you can phase through one block high areas when joining the world.
How to reproduce:
1. Create a world
2. Kill yourself
3. Return to main menu
4. Reload world
5. Try to walk through a one block gap

Observed result:
You can walk through the gap

Expected result:
You should not be able to walk through

Relates to MCPE-155232 and MCPE-109925

Can be used as an x-ray glitch