How to reproduce:

1. Open attached project
2. Open scene TestScene.unity
- The capsule casts in the scene represent character jump arcs.
- The platform is one way, you can jump up through it but you don't fall down through it (if the capsule sweep starts completely above the platform). To achieve this, the collision mask for the CapsuleCast is set differently if the Y velocity is positive or negative.
- The blue capsule shows each sweep that makes up the jump arc.
- A green capsule shows a valid collision.
- A red capsule shows an incorrectly calculated collision.
3. Try moving the CapsuleCastBug gameobject around the scene
- Note how the capsule turns red when the start of a sweep intersects a collider (or when RayCastHit.distance is zero)
- Workaround: ignore collisions where RayCastHit.distance is zero