xdg-dbus-proxy: do you have it installed? maybe try to install again flatpak-runner, that should pull all dependencies...
[nemo@GalaxyNote4 ~]$ sudo zypper se xdg-dbus-proxy Loading repository data... Reading installed packages... S | Name | Summary --+----------------------------+------------------------------------------- i | xdg-dbus-proxy | Filtering proxy for D-Bus connections | xdg-dbus-proxy-debuginfo | Debug information for package xdg-dbus-proxy | xdg-dbus-proxy-debugsource | Debug sources for package xdg-dbus-proxy