I had the waves too, and think I know why. If blocks happen bc of trying to hide it, after a few weeks of increasingly terrible(noticeable!) dysfluency, my brain accepted hiding it had become impossible. So I stopped hiding it and got fluent! Same shit would happen when I went to a speech therapist or when i talked about my dysfluency, usually with lots of unpleasant emotion. My dad has lots of brief repetitions that easily transition to his next sounds, where I mostly had hard blocks bc I was so fearful of ppl hearing my repetitions. Taking w him about it got me MAD. He had no idea what was happening to me beneath the surface. But trying to convince someone how distressing your stutter is *when you suddenly become perfectly fluent!* is a total mindfuck! Tim Mackesey’s podcast taught me everything! Episodes are short, to the point, give you things to try, and enjoyable to re-listen to. Your situation sounds like mine, and I bet with some hard work, you can make *quick and sustainable* progress.