Here is a bug that you can reproduce in 3.5.2 Sketch, the current version:
1. Create a circle, make it any size you want (I made mine 200px)
2. Set a centered stroke on the object (20px)
3. Set the ends to “Curved” and create a dashed line, eg:
4. “Layer – Paths – Vectorize Stroke” In later versions: “Layer – Convert to Outlines”, but this doesn’t change the result
Now, here comes the part that is buggy. If you were to edit this vectorized path and hit “Edit”, the object will be selected like this:
The bottom anchor point will only have one handle, will say it’s “Disconnected”. The only thing you can do to restore the normal functionality is to “Finish Editing”, then re-edit the path again:
If you clicked at the bottom point, it will have its proper two handles that you can work with. Took me a couple of tries to figure this one out.
Additional bonus: if you follow the same process, but set the stroke either to be on the inside, or outside, the vectorize stroke function will not work properly in either cases. If you have a stroke looking on the inside, you can get to an expected result by deleting and recoloring layers that had been created, but if the stroke looked on the outside, it will be a mess.
To sum it up: vectorizing strokes in case of dashed lines does not seem to function correctly and depending on where your strokes had been aligned to, leaves you with various, unexpected results.
update 2017.01.02: this works fine in Version 41.2 (35397)