Hey Frances,
Thanks for getting in touch. To help us troubleshoot the issue you’re seeing, can you try a few things for us? First, can you try disconnecting the plugin from your MailChimp account, then reconnecting it?
If the issue persists, I suggest checking on some details with your host which could be disrupting normal operation of the plugin.
First, try to make certain outgoing connections are being allowed. If outgoing connections are blocked from the WordPress installation, the plugin would be unable to retrieve the lists from the account.
Next, see if you can double check your host has enabled the “fsockopen” php function. This can sometimes be disabled, and is the function used by the plugin to connect to MailChimp.
If you can double check these things for us and changing those settings doesn’t help (or they don’t apply), if you can get back to us with details of your installation that’d be great. Details like WP version, MailChimp plugin version number, and potentially the name of your hosting provider as well. If you’d like to send more details as well which you wouldn’t want to publish publicly here on the forum, you can send an email with your details to wordpress [at] mailchimp [dot] com. In that case, though, we’d still appreciate if you could reply here notifying us you’ve done so.
Thanks,
Gabe