Have you already uploaded the PrePackaged Volumes?
See this discussion:
Going to storage, "Upload PrePackaged Volumes" and select all 4 options
Is your packaging VM joined to the domain? If not, be sure you've configured your AVM to support non-domain entities (disabled by default in AV4).
When preparing your packaging VM:
See the following links for additional recommended practices for your packaging VM:
Verify the ESXi host your packaging VM is running on has access to the datastore where your packaging template and new Packages will be created.
Do you see any specific errors in the AVManager > Activity > System Messages when the failure occurs?
What about the agent logs on the Packaging VM?