In v0.12 I had introduced a 5 second timeout to the web requests for downloading the UO files, thinking that this would help catch bad file download addresses. However, this seems to have the nasty side effect of timing out and killing normal downloads that are just taking some time, because the downloaded files are big.
This timeout has now been removed and hopefully downloads work well again.
The previous "bad" releases (v0.12 and v0.13) have been removed.