When chunks are reloaded after the 1.16 update, minecarts will clip through iron trapdoors when on a rail and move as if the trapdoor was never there. 

Expected result

Minecarts should simply stay put when the chunk is reloaded as if nothing happened. 

Actual result

When first loaded, minecarts will move through trapdoors anyway.

How to reproduce

1. Build a simple rail line with a minecart positioned above an iron trapdoor BEFORE the 1.16 update 

2. Update to 1.16 and reload chunk with the rail line and the cart will move. 

While seemingly a small bug, this utterly destroyed the trading hall that I spent two weeks working on. Luckily, I could use a backup of my world since I have realms, and I have decided to go nowhere near the chunk with my trading hall for the foreseeable future. 

Bug is explained well in silentwisperer's video posted on June 26, 2020 from 20:35 to 21:35: https://www.youtube.com/watch?v=mWVKPz1dpQY