e-Newsletter missing a final "send" button

Hi! I’m excited about the new version of e-Newsletter, but can’t get past the following:

When I reach the page to select my groups, “Select which groups you would like to send to,” the second part of the page that’s supposed to load, as per the screenshots on the plugin info page, does not appear. Basically, I can’t progress toward actually sending my newsletter. Any ideas on why it might not be displaying? The test newsletter works fine.