Retroarch Flatpak Fedora Silverlbue launches to grey screen

I’ve had retroarch working on this computer before. It now just launches the window and just shows a dark grey screen. I tried running on the commandline via flatpak run org.libretro.RetroArch to see if that would give any useful output, but no joy there. I’d love to get this working again - I know you’d need more info to help me, so if there are any particular flags I should use to get it to log to the screen or something, let me know.