Help! Draw on render target texture wrapping not working


I’m creating a dynamic map where character motion path is recorded on the floor as a blue line, based on this tutorial. The core of the system is using a canvas render target and some blueprints to get the actor location and draw additive material at its position every tick.

The trick is working well for simple floor (plain square), however in my case the floor is an imported street network with a lot of stairs and ramps. It seems there is a problem with texture UV mapping where the drawn blue lines are projected correctly neither on the canvas render target nor on the floor mesh. I’m really confused why isn’t it working and any help is really appreciated!

Thanks for advance

actor position traces drawn on the render target (512*512)

whiteboard material (floor material to receive the blue marker reflecting actors’ positions)

marker material (additive)