All horse types with a mob passenger are not looking in the direction they are walking in.
ex. Skeleton horse with skeleton on it.
The horse is walking north, but for example looking east.
To reproduce:
1. /summon skeleton_horse ~ ~ ~ {Tame:1b,SkeletonTrap:1b}
2. Watch while they wander around
Confirmed for 1.14.4
https://twitter.com/theqmagnet/status/1152943204217577472
Also I believe MC-153840 is related and possibly MC-154493
Ridden mobs overall now have issues, they don't turn with the rider, the speed is slowed (seen in video).
This wasn't present in 1.13