It seems that MS pulled it away for now.
I even tried to completely wipe/restore my Surface 2, and only then checking for updates on WU, but with no avail: June 2014 Firmware update is no more showing up in the updates list (Windows RT 8.1 June fixes are all present tough)...
I'm seeing this happening to a lot of people on other forums and topics too, for example -> here
Happening to Surface 2 Pro users too.
Is this happening to you too?
When the new Firmware pack will be available again?