The $\gamma_4$ period divisibility conjecture

Let $\mathbf{M}$ be the move set of a piece $\mathbb P$, with basic moves $(c_r,d_r)$, and set

$$\hat d_r:=\max(|c_r|,|d_r|),\qquad \Lambda:=\operatorname{lcm}\{\hat d_r:m_r\in\mathbf{M}\}.$$

Let $\gamma_4$ denote the fourth coefficient of the quasipolynomial $u_{\mathbb P}(q;n)$. The $\gamma_4$ period conjecture. The period of $\gamma_4$ divides $\Lambda$.

This is presented as an observed low-period bound for a highest nonconstant coefficient; the paper gives no general proof or resolution.