Auto Update failing

I have entered my API and it gives a green status. The plugin was uploaded from the WordPress admin interface and as such should (and appears to) have the correct file permissions. When I click on Auto Update it goes to the plugin upgrade/install screen and returns

Downloading update from https://premium.wpmudev.org/wdp-un.php?action=download&key=ourkey &pid=51…

Download failed.

This is also happening on New Blog Templates. Any thoughts as to what could be the issue?

Thanks.