“Syncing data with the cloud” is not completing

I just noticed several accounts which are obviously spam have been registered on my site despite having installed CleanTalk a few weeks ago.

I tried to start a scan of users but the ‘Start check’ button at /wp-admin/users.php?page=ct_check_users is disabled.

I had a look in the CleanTalk settings and noticed that where it says ‘Syncing data with the cloud. Usually, it takes a few seconds’ is never seems to connect and the icon next to it keeps spinning.

I have subscribed and have an access key. I don’t know when it stopped working.

(Incidentally, thank you for your help on this earlier question: https://wordpress.org/support/topic/updated-to-6-17-now-authors-are-being-emailled-comments-how-to-stop-this/#post-17043354)