I noticed an update yesterday. After it was done, I checked and it had turned off the Alpha testing in the beta test tab area. I paid a hundred bucks...I sure hope I get the new Alpha and Beta loads. Inside Steam options, the Alpha test link is missing.
I think the "live streaming" from yesterday (Friday, June 20) may explain what happened, or at least part of it. During the broadcast Paul said they had found a serious bug at the last minute, which he hoped would be fixed quickly.
If (please note the "if") they had been preparing to make the latest update available and been uploading code to Steam when they spotted the bug they would have had to block updates somehow. I think they would have had to turned off controls that allow updates to be distributed to save us all from getting bad code. From what was said in the broadcast they expect to get the problem solved and the new patch available to us as soon as they can (hopefully in the next few days).
BTW, this is the reason they don't like committing to schedules. They know how bad Murphy can be.