The subadditivity conjecture for plus test ideals

Let $X$ be a regular scheme. Subadditivity conjecture. For divisors $\Delta_1$ and $\Delta_2$ on $X$, one has

$$\tau_+(\mathcal{O}_X,\Delta_1+\Delta_2)\subseteq\tau_+(\mathcal{O}_X,\Delta_1)\cdot\tau_+(\mathcal{O}_X,\Delta_2).$$

This is the mixed-characteristic analogue of subadditivity for multiplier ideals and test ideals. The source says that the local case is proved for a variant of perturbed test ideals, while the stated global assertion remains open.