Given this design,
https://gitlab.com/anelok/mexp/raw/8951232e87fa6c7a8f2820436a2ae9c247dd26a6/alt13/an-top.slvs
all is well with chord tolerance 0.1.

However, if I reduce it to 0.05, suddenly naked edges appear:

The history of plus-base is as follows: I first made sk-minus-base and extruded it to minus-base. Then I added the workplane for sk-plus-base, paste the content of sk-minus-base into it, reattach the now loose constraints, then extrude. Not sure if the copy & paste plays any part in the appearance of naked edges, but this is one thing I didn't do anywhere else.

I also deleted and reconstructed sk-plus-base, this time based on g006-an-side-overlap, but that produced exactly the same result.