Conger's Steiner-point degree conjecture for elliptic Minkowski spaces

Let $\mathbb{M}^n$ be a piece-wise differentiable, elliptic Minkowski space, and let $s(\mathbb{M}^n)$ denote the maximum degree of a Steiner point in a Steiner minimal tree in $\mathbb{M}^n$. Conger's conjecture. For any such $\mathbb{M}^n$,

$$s(\mathbb{M}^n)\leq 2n.$$

The paper gives results for the norms $\lVert\cdot\rVert_1+\lambda\lVert\cdot\rVert_2$ that support the bound in several parameter ranges, while leaving the conjecture open for general piece-wise differentiable, elliptic Minkowski spaces.