When an attributes file for an existing component is recreated by Nexus the "storageItem-storedLocally" property is not set in it. This causes Nexus Firewall to permanently mark the status of the component as PENDING, and it will be blocked for download if quarantine is enabled.
One way this can happen is if a users disk fills up. In that case, in valid attributes files may be written for components, and when Nexus tries to read them in later it will discard them and rebuild new ones, without setting "storageItem-storedLocally".
The only way to get the components out of PENDING state is to delete them from storage. This will cause them to get re-downloaded when they are requested again through Nexus, and then "storageItem-storedLocally" will be set.
When an attributes file is re-created for an existing component "storageItem-storedLocally" should be set to the timestamp of the component on disk.