This is presumably because the ASF download area:
was not set up originally.
This has now been done, and the mirrors will start to pick up the files over the next few days.
All ASF downloads must use the ASF mirror system.
Now that ISIS has been set up, please can you update the download page as per
However, it would be best to wait a couple of days before replacing the page so that mirrors have a chance to catch up.
Likewise, following a successful release vote (and promotion of the files to the dist/release/isis area), please wait a couple of days before announcing a new release. This is so the mirrors can catch up.