This is widely considered the "holy grail" fix for the round corner crack issue. SketchUp was designed primarily for architectural scales (feet/meters), not microscopic tolerances. By tricking the software into thinking it is working on a huge object, you bypass the tiny-face problem entirely.
If your rounding radius is too large for the physical size of the top face, the curves will overlap and cause geometric self-intersection (crashing the face). Lower the radius value. sketchup round corner crack top
Fixing the "Round Corner Crack" on Top Faces in SketchUp Creating smooth, filleted edges in SketchUp is a standard part of 3D modeling. However, plugins like Fredo6's or Corner can occasionally leave a visible "crack," gap, or missing face on the top surface of your geometry. This is widely considered the "holy grail" fix