What is happening?

Can not perform JUMP when touching a block and going FORWARD (just like pushing the block). To JUMP, one must hit JUMP and them move forward.
Also, blocks hitbox seen a little smaller than usual. Why? It's possible, while moving FORWARD, to go like a spider (without moving in Y coord), just like the block has a 'grab' propertie that is activated when pressing FORWARD. The player then drops to floor if FORWARD button  is released.

All tested in grass blocks

In other versions, JUMP was possible while pressing FORWARD and touching a block.