MultiSphereTraceForObjects wrong impact point

I’m using a multispheretrace to detect closest impact points to an actor.
The way I do this is by doing a sweep with a giant sphere over a very small distance.

This works 99.9% of the times, however sometimes the impact point is way off. (video:MutliSphereTraceForObjects wrong impact point - YouTube )
This is the blueprint script doing the trace:

In the screenshot below you can see red and green spheres. Red is on the walkable mesh, green is on a plane below. 1 red circle is way off. This seems to have happened when walking over one of the edges on the mesh:

I double checked the mesh, there are no holes/edges. This happens on multiple locations. Until now always on an edge.
Is this a known issue? Is there any other (better) way of getting proximity points to an actor?

Thanks