Hi @mmirold 
,
Excellent job 
figuring out the solution to your issue on your own. We’re glad you’re able to share your experience with the community.
The “Include in Export” setting for Artboard properties is the cause of the background color being copied alongside the artwork. Disabling this setting will prevent this from happening again.
Kudos for your resourcefulness 
. We’re always here to help, but it warms our hearts every time we see users succeeded in their knowledge journey.
If you’re on the lookout for more insightful tips that may have slipped through, I highly recommend checking out this blog article: 9 things you (probably) didn’t know you could do in Sketch
It’s an oldie but it’s sure to provide you with valuable information.
Cheers 
