I did it on a pretty old installation that I updated to 3.8.1 before installing the plugin. Theme was Spun (from www.remarpro.com) and I had Better WP Security and Contact Form active. After activating your plugin, I could go to the list of charts, which was obviously empty, and after adding a new one, the list was still empty. Deactivating the plugins and switching the theme to 2014 strangely let the GANTT Options page show the list of all the created charts ?? Activating and returning the previous theme did not “hurt” the plugin, so now it works fine.
If you are doing some caching on the charts’ list, this might be the reason… otherwise it may be misuse of a hook or filter in the wrong place, I dunno.