I just (for fun) went through the Remote Access Wizard to see if maybe there was something in there you couldn't set manually. I was surprised to find that they don't allow you to use Domain Names vs IP addresses (via the wizard). They also do not recommend a setup with a DMZ. So if you have a ISP Modem/Firewall prior to your main firewall, you will not be able to get all green flags to finish the wizard. I have a dual router setup, but I have the WAN IP of my inside firewall set as the DMZ IP for my Verizon Router. Shouldn't be an issue; but man I'm not ruling anything out.
OK. ChrisX has the biggest hint here, I just re-read his posts and he seems to have an android and an Apple device. He indicated he has Animated Gifs working on his Apple, but when he flips that one he gets the blank screen on his android. Dasstrum seems to have a similar setup. So we are getting close to knowing WHY this is happening.