I've experienced similar situations, though I don't have nearly as much experience with training as you. My back squat was stuck at a silly low number for a long time. I stopped squatting altogether, started strongman stuff (stones, farmer's, heavy sandbag work). Surprise surprise, back squat went up 30# without touching it for 6 months. It's gone up another 30# since then.
Joe, I try to look at skill which will put my newfound strength to work. Im finishing up a cycle of frequent squatting and pressing, so now I'm going to strongman and o-lifting. Both can be skill dependent enough that it will take me a good while before strength is a limiting factor again. I'll be able to progress at something, without necessarily getting stronger, though I probably will anyways.