The virtual first Betti number conjecture for hyperbolic lattices

Let $\Gamma\subset \operatorname{Mob}(\mathbb S^n)$ be a lattice. Virtual first Betti number conjecture. There exists a finite-index subgroup $\Gamma'\subset\Gamma$ such that

$$H^1(\Gamma',\mathbb R)\ne 0.$$

Equivalently, $\Gamma'$ has infinite abelianization. The source cites substantial progress for arithmetic lattices, but leaves the general conjecture open.