I have exactly the same issue on debian sid: michal@debian:~$ gnome-software
(gnome-software:25795): Gs-WARNING **: failed to open plugin /usr/lib/gs-plugins-9/libgs_plugin_packagekit-origin.so: /usr/lib/gs-plugins-9/libgs_plugin_packagekit-origin.so: undefined symbol: gs_plugin_packagekit_results_valid (gnome-software:25795): As-WARNING **: not adding path /home/michal/.local/share/flatpak/appstream [user-flatpak:(null)] as not a directory gnome-software 3.20.2-2. Tried to purge packagekit and gnome-software and reinstall it. Still not working, there must be a bug. Please reassign or any hint what could be reason of that? I have no any software intstalled outside Debian Sid repo.
