I am working on a Premiere project that will be exported for YouTube. At the end, there is a screen with two boxes in which I've placed clips of my previous videos. These will be annotations on YouTube. The background of this end screen is a timelapse video that I took of a white board drawing being created. So, in order to 'cut out' the boxes where the annotation video clips will play, I used garbage masks. Everything looks great in Premiere. But when I render it, the background white board video disappears. It's just the two smaller annotation video clips on a black background. What am I doing wrong?
TLDR: The clip on which I've placed my garbage mask is rendering black when I export it.