Simply put execute runs the commas at the closest center block coordinate not focusing the command on the player/entity.
There where some others who have the same title or about the same thing but they are talking about how it's not focusing on the player/entities's head but I'm simply stating that it's focusing around the center of the block and not the player as it should be.
Linked issues
Comments 1

I created a bug report for this exact issue recently. See MC-64188