Yeah I had this issue once or twice when developing it but I made the assumption that maybe grunt-watch wasn't catching up or something but someone else has said the same thing.
Do you mind me asking which browser you are using? I developed it using firefox and chrome. Another user has suggested maybe (if my interpretation is correct) getting rid of the intro modal completely which would solve this problem.
I really appreciate the feedback so thank you for commenting.
The screen is also blank (forever) if you have cookies blocked. This is so common that I guess very few people whitelist cookies. Still, I thought you might want to know.