The OCCT have sometimes some hassles with sweeps. But with some experience, yo know what "errors" you can ignore. In that case, i would ignore it. Even when i fillet the edges, it works flawless and fast (instant).
- 2023-03-25_04-38.png (309.17 KiB) Viewed 518 times
The only issue i see, is that you cut the sweep cylindrical coplanar, make the outside of the Sketch a little bit bigger. Since the "cylindrical" outside of a helix sweep is just a very good near of a cylinder, you can get some troubles with that. Generally coplanar operation, especially on freeform shapes, should be avoided (not only in FreeCAD, just said).
Greetings
user1234