I’m having a similar problem with a 480 GB SanDisk EX II on a Z87 desktop mother board, Windows 8 PC.
Just got the EX II, so just have it connected to the PC, not an OS drive. It works fine in all situations except waking from S3 Sleep.
Upon waking from Sleep, the EX II is not seen in Windows Explorer, Disk Management, etc. The EX II does not appear after a minute or so as some other users have reported, but I’m not using it as an OS drive yet. A restart of the PC will cause the EX II to function normally again. It works fine from a cold boot. It won’t wake spontaneously after coming out of Sleep.
I’m using the latest Intel IRST driver, 12.9, and the EX II is connected to an Intel SATA III port. I tried adding the HIPM and DIPM settings in the power options, with no affect after trying various options. I have Link power management disabled.
I have three other SSDs in this PC, and none of them have this issue. I realize that these slightly older SSDs may not have the same options/features enabled that the EX II does, but I’m surprised this issue was never seen in testing. I tried going into Sleep, and waking the PC within one minute, and the EX II is not seen/active in Windows.