Blakc outline when I render the cutout but not the composite

Hey guys, I use mocha on premiere. On mocha, I track my footage, insert a png after it’s done, then I render it to get the motion blur desired. Back to premiere, I go to the module render window, when I render the composite, everything looks fine, but when I render the cutout insert on the base video layer, it adds a black outline around the insert.
Is there something I’m missing or not doing right? If you need more info don’t hesitate to ask.

Are you brining in the Insert from another layer in Premiere OR from file?
Does it help to toggle the Pre-Multiply setting in the Insert Module and re-render?

thank you it worked, I cant answer your first question I’m not sure I understand it ^^
Can you tell me in a few words what this pre-multiplied does? I’d like to understand what I was doing wrong

Hi, you’re better off Googling - Premultiplied vs Straight alpha, It’ll be clear as mud then :rofl::+1: