Queue - timing not working

This is about a post that has just been closed in the "features" list.

The timing of queued items is plainly not working. On one of my blogs I have set it to "every 12 hours" and there is nothing happening for days, then suddenly five items show up one after the other.

On the other blog I have set it to "every ten minutes" which means I should see 144 posts per day leaving my queue and ending up on my blog which never happens. It is more like 70 or so.