Steps to reproduce:

1. Create new project and add empty game object to scene
2. Add Circle Collider to that object
3. Scale that object to have negative scale
4. Enable "Edit Collider" and move any of the handles
5. Notice that collider instantly gets truncated to dot (or more likely - a circle with the minimum allowed radius)

Reproduced with: 5.6.0b3
Not reproducible: 5.5.0p3