Repetitive movement?

Same kind of repeated, seasonal movement of a slab. Notice the widened gap at the break. The mortar joints are consistently wide instead of narrowing at the top or bottom. In other words, movement is downward one time and upward the next sesaon. The problem here is all of the floor is not returning upward with the perimeter beam so there is a noticeable slope of the interior finished floor. Disappointing to say the least.