I only now caught up with the 1.14 snapshots and experienced a strange behaviour concerning minecarts and curved rails.

I loaded up a few worlds I last played in 1.13 or prior and in every one of them minecarts won't go past a curved rail. Straight tracks work just fine - powered ones as well as normal ones.

The bug persists even after breaking and replacing the rails as demonstrated in this video: https://www.youtube.com/watch?v=GyTBt6OOP-0