GSD could not import any of the dials from FVD speed dial. I watched the youtube video of how to import the dials several times and tried several times. All that is imported is the Group headings and no dial headings/url's or anything. Some of my groups have more than 40 dials and I had adjusted the group columns & width to be 6 X 12 dials. Still failed to import a single dial. Waited for an hour for the import to take place - Failed to import. (Though "Import successful" was shown in the options tab and "Save" done.) I tried both the methods described in the you tube tutorial (including unzipping the Speedial.sd file). So help me if anybody knows a workaround.
Reviewed on 28/Nov/2021: I tried again after reinstalling GSD. Did the import of FVD speed dials as described in the developer's You tube video. Pressed "Saved". Waited for a minute. Then shut down Firefox. Restarted Firefox and, lo behold, all my dials in FVD Speed Dial had been correctly imported to GSD, all correctly arranged in the respective groups. All that remained was to refresh the thumbnails in the various ways available in GSD. (This can take some time if you have 300 dials or so, like me).
Finally, changed the "extensions.blocklist.enabled” pref value to true in firefox's "about:config:".
Changing my rating to 5 stars for this extension. I really appreciate the hard work done by the developer. He updated his extension as soon as he came to know of the problem. Wow!