Perhaps you have a backup with GP Premium v1.0 and can see the v1.1 upgrade and could then install duplicator in an attempt to recreate the issue. Create a clone and install it (the clone) on a spare domain or sub domain to see what happens for you and whether or not the update to v1.1 remains available post the clone installation.
Maybe you can then see what is causing the issue?
The reason I use the Duplicator plugin is that 1.) it has well over a million downloads and 2.) its free and 3.) its specified to run on my host (hostmonster) and 4.) the creator of the plugin also uses hostmonster, so it should work really well.
All other themes and plugins appear to work fine. Many of which I have had updates come in for.
Your GP theme all seem to work fine. Its just the GP Premium plugin that I’m having issues with.
NB: I also just had a thought. Maybe you could work with the duplicator creator who i am also going to contact and provide a GP licence, so they can also attempt to recreate the issue otherwise there is likely no way that they can recreate the issue and fix it for other uses of both the duplicator and GP Premium plugins. It may be something to do with their plugin, not yours given the very large number of plugins/themes it needs to be compatible with on WP.org