.gho file won't sync to site server

I have a single site server, and I have successfully created an image. Now, the image is stuck as a "Pending Package". The sync was attempted this morning, but it failed and the package was marked in Site Servers as "invalid"; now, it's just stuck at "Pending".

On the site server, the .gho/.ghs files are available in C:\Program Files\altiris\Altiris Agent\Package Delivery\{4a9deb21-ca50-4b36-8c4a-e845c006a96b}\cache, but the Package Server tab on the agent shows it stuck in "Checking Package".

Everything else works normally, and the logs show nothing suspicious.

Thoughts?

Thanks!