Nontriviality of the spin^c index difference homomorphism

Let $(M,L)$ be a closed spin$^c$ non-spin manifold with $\dim M\geq 5$ and with $\mathcal R^{{\mathrm{gen}+}}(M,L)\neq\emptyset$. Fix a basepoint $(g_0,A_0)\in\mathcal R^{{\mathrm{gen}+}}(M,L)$, and let

$$\operatorname{inddiff}^c(M,L)\colon \pi_q(\mathcal R^{{\mathrm{gen}+}}(M,L))\to KU_{q+n+1}$$

be the spin$^c$ index difference homomorphism. The spin$^c$ index difference conjecture. The homomorphism $\operatorname{inddiff}^c(M,L)$ is non-trivial if the target group $KU_{q+n+1}$ is non-zero.

This proposes a spin$^c$ analogue of the nontriviality result for the index difference homomorphism on spaces of positive scalar curvature metrics. The parser supplies no evidence that the claim has been proved or disproved.