The motivic generating-function conjecture for stable-bundle moduli spaces

Let $S$ be the completed and suitably localized Grothendieck ring of motives over $\mathbb{C}$, and let $\Gamma$ denote the set of characters $\alpha=(n,d)$. For each $\alpha\in\Gamma$, let $R_\alpha$ be the motive of the stack of semistable bundles on $X$ with character $\alpha$, and let $A_\alpha$ be the motive of the moduli space $\mathcal{M}(\alpha)$ of stable bundles. For $\mat{\mutemp}\in\mathbb{Q}$, define

$$R_\mat{\mutemp}=1+\sum_{\mat{\mutemp}(\alpha)=\mat{\mutemp}}R_\alpha x^\alpha, \qquad A_\mat{\mutemp}=\sum_{\mat{\mutemp}(\alpha)=\mat{\mutemp}}A_\alpha x^\alpha.$$

Let $S^{\rm tw}_{\mathbb{L}}[[x_1,x_2]]$ have multiplication $x^\alpha\circ x^\beta=\mathbb{L}^{-\langle\alpha,\beta\rangle}x^{\alpha+\beta}$. Motivic generating-function conjecture. One has

$$R_\mat{\mutemp}\circ\operatorname{Exp}\left(\frac{A_\mat{\mutemp}}{1-\mathbb{L}}\right)$$

in $S^{\rm tw}_{\mathbb{L}}[[x_1,x_2]]$. This is the motivic analogue of the preceding virtual-Hodge-polynomial formula; the supplied text does not state whether the conjecture has been resolved.