Hasta La Motion!

Sorry if this is a nooby question but bear with me. I’m still trying to transition over from AE.

I’m trying to key out a non-evenly-lit greenscreen in multiple takes. Normally how I would do it in After Effects is split the footage up into sections with rough garbage mattes, key each section, then re-combine all the images into 1 by merging the alpha’s.

Whilst creating the first pass in Nuke, the Bezier seems to be creating this thin black edge around where the bezier has been drawn (see attached screenshot).

Second problem is when re-combining the alpha’s, the table seems to go transparent, even though the matte is pure white.

Thanks for the help!