Random raycast/sweepTest failure

I am quite sure that sometime a raycast or a sweeptest will randomly fail at detecting a collision. We are using mesh colliders for the environment so I am wondering if it might be related to that. Did anyone notice something like this? Any idea why it might be happening?

 

If you do a raycast or sweep test against *moving colliders* then the collider positions will only update at the next fixedupdate. In between this time, it's perfectly possible your raycasts or sweeps will miss.

Otherwise its quite likely it's your code.