I just created an action which directly calls PropertyCollector.RetrievePropertiesEx() API method.
I think the problem can be related to the issue mentioned for configManager property in the API documentation:
In releases after vSphere API 5.0, vSphere Servers might not generate property collector update notifications for this property. To obtain the latest value of the property, you can use PropertyCollector methods RetrievePropertiesEx or WaitForUpdatesEx. If you use the PropertyCollector.WaitForUpdatesEx method, specify an empty string for the version parameter. Any other version value will not produce any property values as no updates are generated.
Meanwhile I've seen other places in API docs mentioning the same thing for other properties.