What is going on with Subscription Manifest validity expiring in less than one day?

What is going on the Satellite Subscription manifests becoming invalid in on the Satellite Server less than 24 hours? Every time I sync now, I have to refresh the manifest or download it again. This started happening about 2 months ago, although I thought it was some quirk. At this point it is more than a minor annoyance. I'm running an old Satellite version, 6.3, but I don't understand why the manifest is impacting the sync process like this. It is almost as if the newer versions of Satellite server do a refresh automatically prior to sync, but older version now have to refresh the manifest manually just prior to a sync. Why would something like this be happening??

Sync failure:

Refresh the manifest, you can see the previous refresh was less than 24 hours ago:

Start a new test sync with one repo.

It worked and too about an hour, I start all the others.