Hello Richard,
Did points (1) and (2) of what you wrote earlier. I got an error message on this page http://www.darloup.com/blog/wp-admin/admin.php?page=jetpack-debugger
Jetpack Debug
Test de la compatibilité de votre site avec Jetpack en cours...
Votre site ne semble pas être capable de communiquer avec Jetpack.
Translated into English, it means:
Jetpack Debug
Testing compatibility of your site with Jetpack...
Your site appears unable to communicate with Jetpack.
I'll check the installed extensions...
Best Regards,
Henry