[Plugin: Edit Flow] Scheduler not working

Sometimes we schedule articles and they miss the schedule, other times, we schedule and they go live immediately instead of the status being changed to “scheduled”. other times, it works perfectly. i’d say it works 50% of the time. Several months ago, it worked 100% of the time, so not sure where the incompatibility is. Please help. Otherwise, we love the plugin.

http://wordpress.org/extend/plugins/edit-flow/