Fusion
I encountered a bug which is both very frustrating and fascinating. I'm trying to model fins for a rocket, and to make the edges sharp I'm sweeping a pointy shape around the outline and filling the inside with a rib. I want 3 fins, so I did a circular pattern around the central axis. Well, one of the pattern elements was a perfect duplicate, but the 3rd one had only the sweep, not the rib, making a hollow fin profile:
Curious, I added more fins to see which ones would duplicate correctly, and the results were confounding. Out of 20 fins, 10 of them were correct, but they were distributed seemingly randomly. Here's a visualization of which fins patterned properly and which ones didn't as more fins were added:
Any ideas on what is causing this and how to prevent this weird issue?
