I don't suppose anyone has run into this issue before were VMM inventory tasks that were scheduled on an ESX host are continually put to sleep until they time out.
A discovery on the vCenter has correctly identified all the hosts.
So Sites and Site Servers are properly defined and functioning correctly for all other workstations and servers. The ESX hosts are in a site that has 3 functioning site servers. I even manually assigned the filter 'All ESX servers' to that site as was documented in the VMM 7.1 SP2 User Guide.
What am I missing?