That message means this screen does not have a preview yet. It does not always mean the publish failed.
Wait until the status is completed, then open the task again. The preview is loaded with the task. A row opened too early can look empty.
Check the status first
- Refresh History after the run
- Open the completed task
- If the status is failed, read the error
- If the status is scheduled, the file is not supposed to exist yet
The storefront URL updates only after a successful publish. An unfinished task does not change it.