So I'm not quite sure if this is because GIF's are not being supported or if there is a bug in the system.
Yes, GIF files are supported.
My only guess is perhaps you have hit the maximum number of static files for that Place. I believe the limit is 30 static files per Place.
If that isn't the issue, I would recommend opening a support case with Jive.
Thanks, there aren't 30 in there yet. So I will start asking Jive what the issue is.