Programming for Olympic lift within a CrossFit class is not an easy task. Many gyms avoid it all together now because of the risk with the snatch involved.
I think most members Olympic lifters plateau after awhile for two main reasons.
1. they were not taught proper technique to begin with and have “crafted” their own technique to be good enough to to hang with other class members. Once they realize this and decide they want to become competitive they don’t take the time to rebuild their movement pattern
2. They are not strong enough, many people who love the weightlifting aspect of CrossFit think they need to be doing it year around to improve, when in reality most of them would be better taking a step back from and developing raw strength in their squats, press, hinging and pulling. This is especially true for CrossFit females that have no bodybuilding background.