I spun up a new 2012 R2 KMS server recently. Put in the fancy 2012R2/Win10 KMS key and our Office 2010 key. The vast majority of our computers auto start each day at 6 am but the arm count on the OS was stuck at 24. I even pulled three spares off the shelf and imaged them with Win 7, slmgr.vbs /ato and the count stayed at 24.
Then I took one of them and hit it with Win 10 and the count instantly jumped to 25. So it seems maybe the count only increments when you hit it with Win 10.
