I may have solved the problem. I feathered the mask that rides along the edge of the screen and the lines appear to be gone. I imagine the masking is not an exact, right to the pixel process. If I still have trouble, I will share files. Thanks.
When previewing my video, no edges of masked areas are visible. When exporting, edges show up on extreme right side and bottom of final video screen. I've double checked mask placement and all content is HD 1920x1080 and 24fps. Very frustrating. Any ideas?