Sharing queue remains empty even though settings are correct

I noticed that Revive Old Posts hadn’t shared anything for a week or so, so I took a look at my settings. I can’t identify any settings that might be causing a problem. I have an active Twitter account set. My general settings are filled out, including the categories I want tweeted. The “Enable Google Analytics Tracking” box is checked as “yes”. The sharing box/notification in the right column is active.

Nevertheless I go to my Sharing Queue and see “No queued posts! Check if you have at least an “Active account”, what posts and pages are selected in “General Settings” and if a “Schedule” is defined.”

Clicking “refresh queue” activates refresh queue but still results in “No queued posts”.

And for what it’s worth, no logs are generated.