Maybe the same problem?
Fragments remain after subtracting.
Example:
Rectangle in first plane
Circle or ring in second plane
The rectangle intersects the circle or ring completely.
After selecting "Subtract", however, fragments of the circle or ring remain, which can be seen at the nodes, among other things.
This does not always happen, but I cannot explain where the problem might have its origin.
Left Circle (Ring) is not correct.
Right Circle (ring) ist correct.
My System:
iMac (Retina 5K, 27-inch, 2017)
3.5 GHz quad-core Intel Core i5
Radeon Pro 575 4 GB
macOS Monterey 12.4
Affinity Designer 1.10.5
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