BGDDT

@PointC That did the trick! Thanks so much for your reply ?

See pen - I am using a mask to create the effect that looks like I have cut a hole with a path shape in the blue box to show grey background behind it. I am then using DrawSVG to animate this. All is working fine except on Edge browser. If you comment out the opening and closing mask tag then the DrawSVG animation works fine in Edge. Has anyone come across this issue before when using masks? Thanks!