glass/alpha problems in vrayfinal

just got that odd problem where you apply a glass material and the alpha renders out solid. Has this been covered before and is there a workaround?

alpha renders out normally with standard materials though.

suggestions?

Im not sure I understand. Glass material typically has a refraction. Refraction will have no alpha. For this the refraction filter must be rendered (gbuffer pass).
Otherwise transparency/opacity will be included into alpha.

check affect alpha in your vray material settings.