Created attachment 1779603 [details]
Screenshot of Emacs from Flathub running next to Gnome Software with no listing for Emacs. Flathub repos is enabled (this window is from a separate screenshot and composited in for reference)

Description of problem:
After adding Flathub to Gnome Software, no applications from Flathub are available in Gnome Software.

Version-Release number of selected component (if applicable):
Fedora 34 Silverblue

How reproducible:
I've experienced this twice in a row (I reinstalled the whole OS to test)

Steps to Reproduce:
1. Install Fedora 34 Silverblue, reboot into system, setup account, start using it.
2. Open Gnome Software. Confirm that some application (Emacs or Syncthing or Glimpse, for instance) is not listed.
3. In Firefox, navigate to https://flatpak.org/setup/Fedora/ and download the Flathub Repository File (https://flathub.org/repo/flathub.flatpakrepo)
4. Open in Gnome Software when prompted.
5. Install Flathub repo.
6. Search for Emacs (or any app known to be in Flathub)
7. Try to force Gnome Software to update its listings; close it and reopen it, accept system updates if offered, wait several minutes.
8. Open Terminal. Do `flatpak search emacs` and see that Emacs is listed.
9. Install Emacs with `flatpak install org.gnu.emacs` and launch it to confirm that it's installed.
10. Open Gnome Software again, observe that Flathub is still not found.

Actual results:
Gnome Software eventually detects Flathub as a repo and lists applications, but I'm not sure whether it's just a matter of time, or a reboot, or a log out, or what.

Expected results:
If Gnome Software is awaiting a trigger, it should let the user know.
If a delay in propogation is expected, the user should be alerted.