Quote - I'm pretty sure in P7 that to avoid halos around transmapped items, that even though the background may have been black, you still had to choose 'Render over black' in the render settings.
Does that make a difference in P8? I'm not able to access my P8 box to try it right now.

Yup, that's the way I've always done it. I understood from the above posts that others are also doing it this way, but still getting the problem.

"If I were a shadow, I know I wouldn't like to be half of what I should be."
Mr Otsuka, the old black tomcat in Kafka on the Shore (Haruki Murakami)