You need to track down where in the download chain things are going awry.
In the Bigfix console, look on the ‘Summary’ tab for the action.
There should be a section ‘Downloads’ that lists the files being downloaded together with their status.
If this has a status of Complete and Details say ‘Cached on Server’ you need to look down the chain of relays.
If anything is not Complete, check the details in the Details column.