When you are holding "W" and there is a block in front of you, you can not jump, you will simply stay in place. I have noticed same happends even if you are holding A, S, D and sticked to a wall.
What I expected to happen was...:
I expected to actually jump.
What actually happened was...:
I stayed in a place.
Steps to Reproduce:
1. Put a block in front of you, if there is not any.
2. Hold "W" and stick to the block.
3. Press or hold space.
Linked issues
Comments 4
same thing happens, if you are on a horse. It's really annoying, and I can't go mining like this.
Happening to me too.

Duplicate of MC-142913.
Confirmed with several types of blocks.