Black frames exporting with Da Vinci 15

Hello. I'm starting with my licensed DaVinci Resolve 15, and exporting my first graded project, I find a few black single frames in the middle of a few clips. Before color grading they weren't there.
Any help on that? Thanks

[Peter Chamberlain]

Can you detail your system, OS, and the codec you are rendering.
This might help
viewtopic.php?f=21&t=71894

I’m getting same issues with black frames in rendering output using exr, dpx, tiff and QT DNxHD.
Seems to be only on fusion clips. I downloaded today’s update 15.1 and same result.
Media for initial shots are RED weapon 6k.
Also, project is on a shared DB. Don't know if that makes any difference, but.