I do not know how it is on JP datacenters and how the Cloud Nine map is proving "unpopular" as YoshiP said in the last live letter, but I've been queued up on EU regularly in the past weeks, and CC does NOT happen during volcano map, but DOES spawn during Palaistra or especially Cloud Nine.
So I guess it's stinky volcano map that's unpopular on EU. Do the devs only monitor JP datacenters or what?
I'm not saying this because as a ranged player I like Cloud Nine (I really do), but because volcano is actually NOT popping in the evenings here. Recheck your data, if you care about EU that is?