How to recreate:

Step 1: Stay in middle of a block.

Step 2: Put a Shulker box in the main hand.

Step 3: Turn down and place the Shulker box.

Hypothesis: I would not let you place the Shulker box and you would not move

Reality: The block is placed and you move or sideways or up.

The in the Video (Its a survival world, and i dont haven 5 minutes of i played)