I'm posting this in the public support forum because I think it's important and everyone should be able to read the solution if we come up with one. I'm experiencing a very weird behaviour with custom polygon colliders for sprites lately. Let me show you:
· Step 1: create a sprite collection and draw a custom polygon collider over one of its sprites (as you can see it's a "closed" collider, not an "open" one, like a straight line or something. All vertices are connected. Notice the normals as well).

· Step 2: place the gameObject in the scene and make your character walk over it.

· Step 3: cheerfully watch your character fall into the solid object (I've triple-checked and the Mesh Collider component is NOT trigger, nor is my character).

This is also happenning to me with many walls and other limiters, if their colliders are part of a sprite collection (not Unity built-in ones). I'm using 2DToolkit 2.4.0, any ideas on what may be causing this weird behaviour? The most annoying thing is that some parts of the collider are indeed solid, as you can see in the second image I posted, it's like the box is partially solid and partially a trigger. It seems to happen by pure random.