Etingof's nondegeneracy conjecture for the q-deformed inner product

Let $H_{c,k}(\Gamma_n)$ be a symplectic reflection algebra, and let $M,N$ be finite-dimensional $H_{c,k}(\Gamma_n)$-modules. Define the q-deformed form by

$$(M,N)_q=\sum (-q)^j\dim \operatorname{Ext}^j(M,N).$$

Etingof's q-nondegeneracy conjecture. If $q$ is not a root of unity, then the form $(,)_q$ is nondegenerate.

The conjecture is a q-analogue of nondegeneracy of the finite-dimensional inner product. The paper notes that it is proved for cyclic groups under some restrictions on the parameters by Gordon and Losev, while the unrestricted general case remains open.