Soul sand doesn't behave consistently

Soul sand can affect your movement speed through blocks that are half or less than a half block thick but when you are on half block soul speed doesn't activate

To recreate this bug you need to:

1. make 8 paths half ow them with soul sand as a base block and half with normal solid block without special effects
2. cover the second couple with carpet the third with trapdoors and the fourth couple with half slabs of any kind
3. walk over each of them twice first time without soul speed boots and the second time with them and measure the time of each run