Hi. I'm having a video flashing problem when I use the mask tool on various effects. I did as search and found that a couple of years ago other people had this problem. Obviously a bug. I guess it hasn't been fixed yet. Here is a test clip I did where I put Lumetri color on a clip and made an elliptical mask. This played fine. Then I put another video layer on and put a mask on that. Then I render and played and got the flashing. Usually if I don't render, I don't get the flashing. But when I output I do. Very frustrating when I'm sitting with clients trying to output something and need to find workarounds. I'm on Premiere 2015.3 but this happened in previous CC versions too.