RDF Queue?

OK so, if we queue solo as tank or even heals, most of the time it's instant 24/7/365. Something has dramatically changed with the RDF queue in the last few months and when we que as tank with 1 person, or even 3 dps, it's a 30+ minute queue. Something is wrong with the queue. Has something changed? There's absolutely no reason that if we are queued solo as a tank we get instant dungeons, but when we queue with a DPS or healer it's not instant? This makes the RDF queue broken, does it not? Please fix this immediately as it's a major flaw. If it's instant queue as solo, it should then also be instant if we queue with a party. There's an obvious flaw here.