Hi,

Specifying "<acceptsMultipleTargets>true</acceptsMultipleTargets>" says that the given action can be execute on multiple targets. You should keep this.

In addition, you can add the following property to your "<templateId>vsphere.core.inventory.objectViewTemplate</templateId>":

<variable name="objectListViewSelectionMode" value="multi"/>

Have in mind that the custom objects extensibility has been deprecated and it is encouraged to be replaced with your own implementation.

Best Regards,

Denis