The source for the 7/31 machine is an ISO file I created using the MS Media Creation tool. The source for the 7/15 machine was an ISO I created from an ESD file.

One odd difference I noticed between the 7/15 machine and the 7/31 machine is that with theħ/15 machine, there was a brief period after booting when Personalization changes were enabled, but with the 7/31 machine, Personalization changes are disabled immediately after booting. I do have another VM in which I installed Win 10 unactivated on, so I am continuing with the experiment. Bummer! I was looking forward to seeing if there was any change after the machine had been running for 30 days unactivated. The VM in which I installed Win 10 unactivated on somehow got corrupted and I had to delete it.