Open a new browser tab and go to:
One of the bases will not be in a "READY" state (vm_bases_state_text) but shows as "INIT" state type.
Note the "vm_bases_vmb_id"
Login to the MAA via ssh using the g2 user.
Run this command to delete the failed base image from the database:
curl -X DELETE localhost/rapi/system/vm/bases/<vm_bases_vmb_id>
Now you can refresh the Manage Activations page and start over.