Render Target Painting - unintentional tiling effect

Hello everyone!
This is my first post here and I hope I’ve found the right place to post it. I’m new to Unreal Engine 4, so I also might not be able to express my problem as clear as I should… sorry for that in advance.

But here we go:
So I’m trying to do some Ingame painting (to be more clear: scratching of color layers by painting with alpha masks) by the render target function. Therefore I followed this awesome tutorial by Peter Stefcek. (Unreal Engine 4 - Blueprint Texture Painting - YouTube)

By working with a cube mesh as my canvas, this works pretty cool. But If I replace this ‘cube dummie’ by inserting a more complex mesh - basically an ancient arc architecture, consisting of many individual parts, which I merged by the Developer Tool ‘Merge Actors’ - I get some really weird results.
To me as a Unreal Engine 4 beginner, I would suggest that there is a problem with the Find Collision UV node placed in the 'TraceFromActor"-function, seen at 9:39 in the linked tutorial.

I’ve attached an image to show you the result I get.

And that’s the arc I mentioned.

Are there any ideas how I could get rid of this problem?
If you need further information of this project just let me know.


Solved this issue by myself. The trick is to use a differend method (harvest geometry from selected actors and merge them into single mesh.) while merging multiple static mesh actors.
Additional to this I activated under proxy settings “Create Collision”, and “Generate Lightmap UVs” and deactivated “Reuse Mesh Lightmap UVs”.
This removed the tiling effect and lets the user only paint / scratch where he is aiming at.