If the top face is even slightly warped, the plugin cannot cleanly intersect the new rounded corner with the existing face.
A common mistake is using too many segments (e.g., 12 or 24) for a small corner. Lowering this to 6 segments is often enough for a smooth look while keeping the geometry manageable and less prone to breaking.
If you have already closed the plugin and just want to fix a single missing triangle manually: Go to to reveal the underlying mesh. sketchup round corner crack top
For more advanced, robust rounding, use FredoCorner, which often handles complex intersections better than the older RoundCorner. Alternative: Round Corners Without Plugins
Solving geometry tearing, missing faces, or visual "cracks" when using tools or plugins like RoundCorner Physical repairs: If the top face is even slightly warped,
This comprehensive guide explains why these cracks happen and how to fix them to ensure clean, manifold geometry. Understanding the "Crack Top" Issue
If you are running into this issue, try these troubleshooting steps before giving up on the model: If you have already closed the plugin and
Pass the eraser over the stray diagonal cracks to hide and smooth them into a single continuous surface.