I’m using the built-in collision system, and I’ve hit an odd problem: While a CollisionCapsule appears to collide with an object that uses CollisionPolygons (specifically, a polygonal collision-model made in Blender), the resultant collisions are sometimes incorrect.
Now, the manual does indicate that such collisions are not supported. However, the engine seems to think that they are: I get no errors, and collisions are detected.
Something that may more may not be relevant is that the capsule is a child of a few other nodes, and is being moved around the scene by those nodes.
Less likely to be relevant, but mentioned just in case, is that the collision-handler being used is a CollisionHandlerQueue.
In a quick test, it seemed that a CollisionSegment worked as expected.
A few screenshots depicting the issue, with collision-visualisation turned on and the collision-objects in question shown: