Can't install personas in LO6.2.2.2

I was able to use personas in LO6.0.7 on LinuxMint 19.1 Cinnamon. Due to a bug in LO (drops music in the slides of Impress), I removed LO and reinstalled a more recent version from the FlatPak-repositories. LO is working fine and the problem in Impress has been solved. However, installing personas doesn’t work at all. Entering the name of the persona, nor entering the according URL doesn’t work.

I found a folder with older personas in $HOME/.config/libreoffice/4/user/gallery/personas

I tried to edit the persona-keys Tools > Options > Advanced > Open Expert Configuration and set the Persona-key to own
and PersonaSettings to the location of a persona-image, but that didn’t work either. Any idea how to install the firefox-personas?

The Personas support has changed in 6.2 due to the changes in the Firefox support. You will find the new default Personas, in my Linux/Mint system in opt/libreoffice6.2/share/gallery/personas folder. Their description is in the personas_list.txt file.

The expert configuration currently allows you to define your own Personas using DEFAULT rather than OWN and the format has changed so this provisionally works on my system with a definition such as default-personas;Default-Personas;default-personas/preview.jpg;default-personas/default-header.jpg;default-personas/default-footer.jpg;#0000ff;#000000 where the first parameter is the folder, the second a provisional name and the other parameters as before.

This approach did not work on the pre-release system but does on the 6.2.2.2 version.

====== update

My personas on my linux/mint system is stored in the .config/libreoffice/4/gallery/personas/default-personas folder. The folder will

There is information defining the problem on Bugzilla Bug 123228 selection from Firefox themes (own theme) no longer works ( Firefox changed the API & removed the footer images) amongst others.

It is not clear to me yet where one has to store the firefox-personas nor how to get them in a trivial manner.