I noticed you have a V-Studio 100. IIRC the 8.1 drivers don't work with Windows 10; you have to modify the .INF file.
Try to borrow an ASIO interface. Set a System Restore point, install the interface's drivers, and use that for a while to see if it fixes the problem. It's sounding more and more like something hardware-related; software doesn't just decide to change pitch, and given that this particular problem has not been reported by others, it's likely system-specific.

Do you have another interface or soundcard you can try? Your V-S could be crapp!ng out.
 
FWIW I had a similar problem that turned out to be my Novation keyboard sending erroneous pitch bend messages. I would have sworn in court that I had eliminated it as the problem during troubleshooting. Took me weeks to come back around to it, but when I disconnected it and left out again the problem was gone. So...
 
Make sure that the input on midi tracks that are complete is set to an unused port / channel (not none). 
 
-edited for whatever that was-

Sorry for the delay in responding. I've been fishing!
 
I'll give all your ideas a go and see if they fix things. Regarding the Win10 drivers. I've no idea which ones are being used as the VS-100 updates itself according to Cakewalk/Roland but it's interesting to note that it worked fine with Win 10 for several months until the most recent O/S updates. It's a bummer because everything else is working just right and Platinum seems like a smashing product, particularly the Mix Recall.

Just a little more info for anyone who hasn't yet ruled out controller-generated errant pitch bend messages:
 
I could see midi activity on the track meter for any midi track set to receive data from the suspect controller, and sure enough both in Midi OX and when I armed one of the midi tracks pointing to that controller and just recorded with no playing of any notes - ZILLIONS of pitch bend messages were recorded.
 
So, after farting around with filtering and such for a little while, I just went to the controller and temporarily turned pitch bend OFF, and the issues immediately went away.
 
Bob Bone
 

Without wishing to tempt fate, I've disconnected the Alesis Q49 controller and things seem to have stabilized without it's contribution. It must be an issue between it and the latest Win10 updates. Perhaps Alesis haven't caught up yet (or don't plan to for this model). At least it's a relatively inexpensive item to replace if push comes to shove!