I have the same problem with HDDs not spinning down and refuse to sleep with all the latest versions of RST on Windows 10 64bit & z87 chipset (Asus Maximus VI Hero).
Please Intel understand that many of us use RST to get optimal performance also for our SSDs and HDDs running in AHCI.
Reverting to default Windows 10 driver solves the problem but I would really like to be able to use RST for best performance as in the past.
Thank you for contacting us. On this particular case, my recommendation is to contact your system manufacturer. They typically provide software which is specifically configured for your system. Intel drivers are generic.