openSUSE Tumbleweed, Gnome Desktop and Hydrapaper

I am running openSUSE Tumbleweed with the Gnome Desktop. I can install Hydrapaper via flatpak, and it initially runs fine. However, after the initial launch, it fails to run again. I’ve tried writing the owner of Hydrapaper, Gabriele Musco, but he has yet to respond back to me about the flatpak application not running.

I know he’s busy, but I’d like to use the application and have it run. Does anyone have any ideas how to get someone’s attention to get this fixed?