If I'm not mistaken, what wrong with your RRF is called "bottlenecking", and is a result of "over stabilization", or too much inbreeding. I first heard about it in a "special" issue of skunk a while ago, in an article by The Rev. He attributed it to mostly selfing to obtain feminized seeds, and of course over inbreeding to stabilize traits, reducing viability. I've had it happen a few times, and know about everyone who grows has at some point. Who knows