My mac is El Capitan, 10.11.6 and Firefox is 53.
This problem ( blank page ) occurs every time with my builds on all browsers using Mac, if I don’t use canvas tag. The page shows blank, however the buttons will click, if I try to click randomly on that page and sound too will play fine. It’s just, that the content doesn’t show at all.
As soon as I use canvas tag, it displays fine. In your case too, I think, that you have not used canvas tag in the project.xml .