Just received August statement - Points calculation looks good!
I just received my SPG Amex statement with the statement closing date of August 13.
This statement had SPG/Marriott stays on it both pre- and post-August 1. The points calculation is correct!
I also prepaid a small amount of Vistana maintenance fees on August 1 to verify the future points earning on those and I'm happy to report that I earned 6x points on that amount.