Hey, with all these complicated scripts and solutions, why has no one mentioned the Push Modifier? It does exactly what you're asking about, no hassle.
Ah, you're right, I was in subobject mode by accident. It turns out that resetting the xforms and adding a Push modifier removed the black marks. Thanks!
2.1.5's hotfix was pushed out but got recalled - it just wasn't updated on the site on a specific area of it. Fingers crossed for a release within the week.