Hey,
could you solve that problem already?
If not, you could try this:
Get the position of your mouse. That’s your screen space location. Then project the screen space location into world space, which yields the world location and the world direction at the screen space position. Then use the world direction and multiply it by 1000 (or something) add this vector to your world location and then you have a ray between the world location and the sum of those vectors (start and end point of the ray). Then you can use the ray in a LineTraceByChannel node. Set the trace channel to an own trace channel (you can specify them in the project settings under Collision) and add a blocker volume which blocks that trace channel.
This solution works great on PC… On Android it doesn’t work, though, because the mouse position is somehow substituted by a GetInputTouchState-node. The touch input node, however, never receives an input event, because the umg button consumes that input somehow. Haven’t found a solution for that yet. Maybe you have an idea?