azslow3
If Input/Output ports disappear, you normally also should see the name of the Control Surface plug-in in brackets. That means either you do not have 64bit version of the plug-in or it can not be loaded.
The list of available Control Surface plug-ins is common for 32 and 64 bit, but 64 Sonar can not use 32 bit plug-ins (bit bridges used to run 32bit VSTs in 64bit hosts can not be used for CS plug-ins).
What you're saying makes sense, yet it doesn't account for the fact that in Win 7x64 StudioMix does work. So actually since you've noticed the same thing with the ports disappearing, I believe this is a bug in Platinum and Win8x64 otherwise Win 7x64 would have the same problem.
Since you have Win 8x64, please try this simple test. You don't have to have any of these control surfaces installed to do this test. Open preferences, use the X to delete any control surfaces you have. Then choose control surfaces (yellow icon), choose studiomix, then choose the midi ports. Hit ok and see if the ports disappear.
Then try manually adding the ports, hit apply, and see if they disappear. The same problem is there for Edirol, Tascam US 428 and Radial. It works fine with ACT and Mackie. If the ports disappear like they do with me, this is clearly a bug with Platinum and Win 8, since this does not happen in Win7x64. Please try this.
Thanks,