Unabe to Sync with RedHat's CDN with manifest - Error Retrieving metadata

Problem:
For a few weeks I’ve had issues syncing all of my Red Hat Products with Red Hat’s CDN. The sync stops almost instantly, saying that there is No new packages. The error RPM1004: Error retrieving metadata: Forbidden is also shown. However, if I remove the manifest from foreman, I am able to sync with cdn.redhat.com without any issues. All of my foreman traffic goes through a squid proxy to reach out to cdn.redhat.com. When I receive the RPM1004 error, no traffic is passed through the proxy. When the manifest is missing (and the sync works fine), I see the expected traffic traversing through the proxy.
Expected outcome:
Prior to a few weeks ago I was able to sync my Red Hat Products with Red Hat’s CDN with the manifest isntalled in foreman.
Foreman and Proxy versions:
1.15.6
Foreman and Proxy plugin versions:
foreman-proxy-1.15.6-1.el7.noarch
Other relevant data:
[e.g. logs from Foreman and/or the Proxy, modified templates, commands issued, etc]

I’m having the same issue in 1.16.0 after replacing my manifest with a new manifest (our old licenses expired). I am not using a squid proxy other than the one integrated into the standard Katello install.

This seemed to resolve the issue for me:

https://access.redhat.com/solutions/3047741

(TL;DR - refresh the manifest after you import it)