AppFabric monitoring database - ASEventSourcesTable is not being populated

Question

A follow up from this original post here.

The specific problem is that the ASEventSourcesTable is not being populated, therefore resulting in no events arriving in the ASWcfEventsTable table. If I manually insert what is required in the ASEventSourcesTable table (going off another AppFabric install etc where ASEventSourcesTable is populated automatically), then events are arriving and are visible through the dashboard (therefore suggesting all the moving parts are working - service, sql agent etc). 

Any ideas on what would be stopping AppFabric 'parsing' IIS to determine what is a valid event source? Something in the config?