Unable to add a site from Chrome Mask's option page

Chrome Mask 8.0 / Firefox 115.33.0 ESR No problem adding/removing a site from the popup when visiting a Website, but adding it manually from Chrome Mask's option page is impossible here: typing the domain name and clicking on 'Add Site' does not add the site. The culprit may be the old version of Firefox: 115.33.0 ESR This said, Chrome Mask runs perfectly well and does the job flawlessly.