Healing brush tool: How to get rid of black outline?

I'm making a digital design which starts with an AI vector that is then painted in Corel Essentials 5, saved, and finally, re-opened in Photoshop to clean up.  I'm trying to fill in white areas along the vector outline with the healing brush tool, but it keeps leaving a black outline.  It's almost as if the healing brush is picking up the original black vector line, but I'm not working on the original vector line layer - the original vector layer is turned off as well as above the layer I'm trying to correct (I tried deleting it too, but it didn't help).  I usually set the Healing Brush Mode to Replace and Sample to Current Layer, but after encountering this problem, I've tried every configuration to no avail.  Any suggestions?