If you are seeing the following in your MICS logs on your CORE/VSP when you are trying to download an update package and you ARE able to authenticate but UNABLE to download:
Downloading Packages:"
2015-08-06 00:57:19,716 ERROR [MICSController] (http-bio-127.0.0.1-9081-exec-6:) Error : For input string: "1.4 G
Downloading Packages:"
2015-08-06 00:57:21,717 ERROR [MICSController] (http-bio-127.0.0.1-9081-exec-1:) Error : For input string: "1.4 G
Downloading Packages:"
2015-08-06 00:57:24,136 ERROR [MICSController] (http-bio-127.0.0.1-9081-exec-9:) Error : For input string: "1.4 G
Downloading Packages:"
Then this means that there is network connectivity issues and you will need to confirm 100% connectivity to https://support.mobileiron.com. Once this is resolved the package(s) will be downloaded successfully. Stage for install then reboot.