Bass's conjecture on Davenport and Gao constants of metacyclic groups

Let $C_n$ be the cyclic group of order $n$, and let

$$G_{m,n,s}=C_n\rtimes_s C_m=\langle x,y\mid x^m=y^n=1,\ yx=xy^s\rangle$$

be a metacyclic group. For triples $(m,n,s)\in\mathbb N\times\mathbb N\times\mathbb Z$ with multiplicative order $\operatorname{ord}_n(s)=m$, write ${\sf d}(G)$ for the small Davenport constant and ${\sf E}(G)$ for the Gao constant. Bass's conjecture. For every such triple,

$${\sf d}(G_{m,n,s})=m+n-2\quad\text{and}\quad {\sf E}(G_{m,n,s})=mn+m+n-2.$$

These equalities attain the general lower bounds for the metacyclic group $G_{m,n,s}$; they are known for dihedral and dicyclic groups and for groups $G_{p,q,s}$ with $p$ and $q$ prime, but the conjecture is otherwise presented here as unresolved.