It may not be widespread, but there is at least one other machine that falls apart like that in almost exactly the same way as yours. He was posting video of it, but it was the same. It would pass movement test, then go to start print and the rods would suddenly go 17 different directions and the whole thing would come apart.
We have not (at least that I am aware of) heard from him again after he contacted FLUX Support, so they may have resolved the issue or he may have given up. Please don't give up. There are not too many things that can cause this, and apart from an actual firmware issue on one of the boards it is most likely something you can figure out and fix.
The quick test you should do right now is download the oldest FLUX Studio available (0.6.3 I believe) and install that. If you want to dual install or overwrite is up to you, it won't matter much in the long run. That older version does not have the 3/4 circle priming extrusion before printing. If you can successfully print with that version, then it is completely a perimeter issue and we can narrow it down to the specific bit of hardware causing the problem.