I have a site running Umbraco 7.3.4 that needs to use the Scheduled Publish / Unpublish functionality. Unfortunately this is not working.

By not working, I mean that items do not Publish / Unpublish at the times they are scheduled to. The date / time that was defined remains populated in the relevant Publish / Unpublish field.

The site runs behind a load balancer, although is not actually load balanced (it runs behind a load balancer because it uses a secure certificate and our hosting environment requires a load balancer to use one).

The site runs fine in our Dev environment and also fine in our Pre Live environment, which is also load balanced, so I've some experience configuring umbracoSettings.config (web.routing/umbracoSettingsUrl) to get this functionality to work in these situations.

I've enabled full logging in log4net.config but the logs don't reveal anything at all. Here is an example:

2016-03-03 14:40:52,303 [P8004/D2/T55] DEBUG Umbraco.Web.Scheduling.BackgroundTaskRunner - [ScheduledPublishing] Task added Umbraco.Web.Scheduling.ScheduledPublishing
 2016-03-03 14:41:52,316 [P8004/D2/T12] DEBUG Umbraco.Web.Scheduling.ScheduledPublishing - Scheduled publishing executing
 2016-03-03 14:41:52,316 [P8004/D2/T54] DEBUG Umbraco.Web.Scheduling.ScheduledTasks - Scheduled tasks executing
 2016-03-03 14:41:52,316 [P8004/D2/T54] DEBUG Umbraco.Web.Scheduling.ScheduledTasks - Scheduled tasks complete (took 0ms)
 2016-03-03 14:41:52,316 [P8004/D2/T54] DEBUG Umbraco.Web.Scheduling.BackgroundTaskRunner - [ScheduledTasks] Task added Umbraco.Web.Scheduling.ScheduledTasks
 2016-03-03 14:41:52,316 [P8004/D2/T40] DEBUG Umbraco.Web.Scheduling.ScheduledPublishing - Scheduled publishing complete (took 4ms)
 2016-03-03 14:41:52,316 [P8004/D2/T40] DEBUG Umbraco.Web.Scheduling.BackgroundTaskRunner - [ScheduledPublishing] Task added Umbraco.Web.Scheduling.ScheduledPublishing

I've searched a lot through previous posts for similar problems with no luck. I'm totally stumped with this. Does anybody have any ideas?

Thanks, Seán.