As the title suggests, I am having this issue.
It worked perfectly when we tested it on LAN, but little did we expect that it would not work on WAN.
I tested on Mac and PC, IE, Safari and Chrome. All are experiencing the same issue -- the viewer is blank showing a grey background.
I've changed the container setting to Open/Secure, External/Internal. It did not help at all.
FMS setting is Progressing Download enabled but without SSL.
If you perform a search on the forum, there were discussion on this issue, but there was no solution to it.
I hope someone who has worked it out could enlighten me.