Try deleting the .xml files and cache from the GUID folder on the package server, then update policy, then refresh packages. Does it redownload successfully and appear valid?
If not, try also deleting the codebase from SWDPackageCodebase:
SELECT * FROM SWDPackageCodebase
WHERE PackageId='GUID of the package from your screenshot' AND
Source='GUID of your package server'
After confirming you get a single correct result (or two for HTTP plus UNC), change SELECT * to DELETE and you will delete it. Then again delete the local files and update the package server's policy, refresh packages, and resend status.