A fresh install of Windows 7 Ultimate SP1 64-bit. All settings are checked off so yes Global drive letters for RAM volumes is turned on in the global settings.
I initally made an 8,000 MB ramdisk and sure enough the ramdisk was there upon Windows booting up. I then increased the size of the ramdisk to 30,000 MB and the ramdisk did not show when Windows finished booting.
I did some testing and it seems that having a ramdisk larger than 15,599 MB does not show up upon Windows booting.
I will revert back to 3.3.3 in the mean time.