Bug By Blackstone Stairs

Hello Mojang Team

First i have to say That my english is Not so Good Bit there is a Bug you cant Walk over normal Blackstone stairs you have to Jump so you are very very Slow and ist is Not a Good feeling (Here is a link to See how ist Looks https://share.icloud.com/photos/08v9oHClD-NX5s9rcUmugEgQw
Please fix ist
Thanks