Put the summary of the bug you're having here
What I expected to happen was...:
I am expecting the Strider to jump up but instead it can't.
What actually happened was...:
I was riding a Strider on a survival world and it can't seem to jump up soul sand.
Steps to Reproduce:
1. Ride a Strider
2. Try to jump up Soul Sand
3. Can't do it
What do you mean with "climp up"? A strider cannot climb up vertical walls, do you mean they can't jump?