Why does searching for a virtual machine assigned to a tag return no result and requires a restart of ovirt-engine service in Red Hat Enterprise Virtualization?

Issue

• When using the tag functionality of RHEV to map thinclients to a virtual machine a vm query of the tag returns no result but a tag query of the VM returns correctly.

[RHEVM shell (connected)]# list vms --query tag=thinclient-1

[RHEVM shell (connected)]# list tags --vm-identifier vd01

id         : ec9f6a6c-0666-11e3-9235-476929d95925
name       : thinclient-1

• After restarting the ovirt-engine service it works correctly.

[RHEVM shell (connected)]# service ovirt-engine restart
[RHEVM shell (connected)]# list vms --query tag=thinclient-1

id         : f0888228-e696-4188-bc84-903356174f8f
name       : vd01