Hi - I'm seeing that big yellow message at the top, "Warning! Garbage collection is not scheduled!"
So I tried scrolling down the advanced page, Selected "Timer", hit the blue Update button, but it reverts back to "Clock" with a setting of 00:00 (screenshot), and the yellow Warning! remains.
I also tried leaving the selection on clock, and setting a time, like 03:00, but same thing. Click "Update" and it reverts to 00:00. Warning remains.
So I installed the Cron View plugin. I see these two lines, and I'm not sure if these are for super cache or for something else... wp_scheduled_delete and wp_scheduled_auto_draft_delete (screenshot)
Any idea how to fix this???
By the way - I'm running WP Multisite, with super cache 'Network Activated'.