If possible it would be good to approach each issue individually, that way we can be clear there’s no confusion between different file/feed types.
ZIP Files
In order to retrieve zip files from an artifactory feed using an external feed within Octopus, you should use a Maven feed from within Octopus.
As mentioned in the post that you linked, maven requirements will need to be met for this to work correctly.
NuGet packages not found
In some cases NuGet packages aren’t found by a feed due to them being missing from the index.json inside the feed.
We have a great troubleshooting guide for NuGet feeds, if you haven’t seen it already, which goes into detail about this: NuGet Feeds - Troubleshooting.
A good test for this could be to see if the package can be pulled from the feed outside of Octopus, or to pull the index.json from the feed and inspect it to see if the package is listed correctly.
I noticed you mentioned certain paths causing an issue and when you moved a package to a different folder it was retrievable from the feed, I’m not certain the cause of this, would you be able to go into more details, please?
I hope this information is helpful, please let me know if I’ve missed anything or if I’ve misunderstood any details you’ve provided.