Thanks for your effort and thorough report here.
Their theme actually claims compatibility/integration with our plugin.
I’d guess there’s a console error at your site on the wp-admin page where this should appear but doesn’t. If not a JavaScript error in the console, possibly a WP_DEBUG error.
Whichever it may be, I don’t have a way to obtain that theme or specific plugin of theirs, and especially since they claim integration with our plugin, you should report this conflict to them.
Please let me know if there’s anything more you think I can help with on this topic.