As above, "Randomise Start Points on Perimeters" doesn't work on single extrusion perimeters - it will start the extrusion in the same place every time, like it's stuck on 'fastest' setting, leading to an unsightly seam or buildup if start/stops aren't perfect (such as with larger nozzles that drool)
4.0.1 - I've had this issue for a long time, it's very easy to generate in a few files, here's one, perimeters all have the same start points, even without being singles.
There's obviously some interaction between settings coming into play....because if you uncheck the "Print islands sequentially without optimization" I think you'll get what you're wanting.
What I'll get is an overheated mess from it slapping two layers of plastic down consecutively on one part.
There's no logical reason that setting shouldn't allow randomised start points.