Firefox (Flatpak) bug in Silverblue 38?

I’m having a problem with the Flatpak Firefox, it started occuring on Silverblue 38. Has anyone run into this before?

Steps to reproduce:

  1. Click Firefox icon in dash. Cursor shows loading circle, then nothing happens.

  2. Click Firefox icon in dash a second time. Error message is shown:

“Firefox is already running, but is not responding. To use Firefox, you must first close the existing Firefox process, restart your device, or use a different profile.”

  1. Wait a minute or two and Firefox opens.

Troubleshooting I’ve tried so far:

  • Created new Firefox profile.
  • Still broken, so I ran flatpak uninstall --delete-data org.mozilla.firefox to uninstall Firefox Flatpak and clear all data/cache.
  • Then I reinstalled Firefox via Flatpak, and problem persists.

Any suggestions on how to debug this?