If you attach a decal in C++ with SetupAttachment() or AttachToComponent()
or if you use AttachToComponent or AttachToActor node in BP
totally if you want to attach this component to another Component or Actor …
The attache SceneCaptureComponent2D can’t render decal !
Well it seems to render correctly in the test project you provided, so I am not sure what you are reporting. I even set the ‘Scale Rule’ for the AttachToComponent node within your blueprint to different settings and the decal rendered as expected.
Perhaps I am not understanding what you are saying, but it seems like you found the solution to the issue. It is expected that you need to provided a scaling method when spawning the actor and attaching it to an actor.
in my test project there’s a SceneComponent that i use to attach the spawned class (class that have SceneRenderComponent) to that, if i change that SceneComponent scale the SceneRenderComponent can’t render decals as you can see in 1.jpg in my comment.
My problem still exist in my main project because in my other project I’ve to attach SceneRenderComponent to a scaled parent so it wont work!
for now i used an alternative way, I set the location & rotation of parent to my SceneRenderComponent in tick function!
Thanks for the clear and precise repro steps. I was able to confirm what you are reporting and have gone ahead and entered a bug report for the issue. You can track the report following the link below on our public issues tracker.