That says it all.  I always freeze midi synth tracks so I can unfreeze and edit them in the future.  Since the latest update of SPlat, the freeze/unfreeze button is grayed out and will not operate.  Even more frustrating, some midi tracks and synths have simply vanished.  They are not archived or otherwise hidden.  I had two adjacent midi tracks going to a aux track, and I froze both tracks yesterday and saved my session.  Today, one of the tracks is gone, and the other won't unfreeze.  Any suggestions?
 
I'm running Windows 10 with the latest updates, along with the updated SPlat on my Sweetwater Creation Station.  Any help would be appreciated.  Thanks.  

Can't really help but I have been freezing and unfreezing tracks this week in the latest version of Sonar. What virtual instruments have you been using?

Rapture Pro for one, and it's completely disappeared, along with Native Instruments Rounds within Reaktor.  Then, NI the Grandeur piano in Kontakt 5 refuses to unfreeze.  I've used all three of these for years, constantly freezing and unfreezing, and never had an issue before.