can you try restarting vCenter Inventory Service and VirtualCenter server service?
Also try the following steps from the KB VMware KB: Datastore appears empty from the datastore browser
To resolve this issue, remove all the invalid references to the old datastore name. The following objects can reference the datastore:
- A registered virtual machine.
- A registered template.
- A host on which the datastore appears on Datastores list, even when the storage device is no longer accessible.
To remove these references:
- Go to the Datastores view.
- Select the invalid, nonexistent, old, or removed datastore.
- Select the Virtual Machines tab.
- Right-click all of the virtual machines and templates and click Remove from Inventory from the context menu.
- If the datastore is still visible, click the Hosts tab (to determine which hosts still 'see' the invalid datastore).
- In each of these hosts click Configuration and Storage, then click Refresh.