Getting “No open CL devices found” when opening Darktable

I installed Darktable 4.6 on my Linux Mint 21.3 (Ubuntu) laptop but when I open it I, very briefly, get the “No open CL devices found” message. None of my photos will load into the Darktable library from an SSD. I removed the Flatpak version and installed version 3.8.1 outside of Flatpak and it all works now. However I’d like the latest version. Any suggestions or work around?

Many thanks.