The bug
A minecart with a display tile, doesn't turn correctly. For example, when you push a chest minecart around a rail corner, the block's front will turn 180 degrees and back, not sure what rail causes what turn. This bug is probaly caused by the displayTile that doesn't turn with the "front" of the cart since in older versions of minecraft, there was no need to specify a front of a cart
How to recreate
Make a circle of minecart tracks, spawn a minecart with chest (or any other non symmetrical texture displayTile) on that rail and push it over the rails. At the corners, you will see the the block turn 180 degrees and back.

Why this is important
I'm trying to make something really cool using minecarts, but this bug stops me from doing that. I'm a young programmer who was inspired by minecraft and it's mods to start programming himself. I'm now working with an NMS minecart and custom resource pack, but this bug stops me from creating something awesome: A sled game

Thanks for reading <3