I finally updated my Win10 to Win10 Creators edition, and just after doing that a handful of my VSTs stopped working.
Notably, MOTU Ethno and Symphonic.  Other small VSTs continued to work fine.
When I try and add the VST it just spins and hangs up.  
I reinstalled the MOTU stuff and now they will invoke as a standalone, but not when they are added as a VST.
 
Has anyone had issues with Win10 creator update, and how did yo solve them?
 
(I already contacted MOTU, and they weren't much help.)
 

I do believe it's a problem with Sonar and not Windows! I have the same problem but in Cubase and Reaper they work just fine. Run Sonar in Administrative mode and your plugins should work!

 . . . after my Windows Creators update , a whole host of issues, mostly device related . . . as far as VST's, mine all seem to work the same, so far, except Spectrasonics Omnisphere. Every time there's a major OS update, I have to rummage through my papers to find the login and password to re-authorize Omnisphere . . . thankfully, I don't have to re-install it . . . so just wondering if this is what you're up against with MOTU ?

With MOTU I think it got messy.  Because I used to run Sonar Home 6XL and installed MOTU for that.   I then fell in love with Reaper (I disliked Sonar so much. :s  ) and just linked the MOTU stuff in.  When I upgraded from Win7 to Win10, there were absolutely no problems.  Its just this Creators update thats knocked a few things off.
Not just MOTU but a handful of other VSTs as well.  The others seem solvable by a reinstall or reauthorisation,  but MOTU hasnt.
I tried running as Admin, and even installing as Admin with compatibility modes etc.  No joy.  

Have you tried turning off "Game Mode", as suggested in the Cakewalk sticky above ?
 

Just turned Game mode off globally, rebooted, still same issue.
 

I had the same problems with a couple of NI products, Komplete Kontrol and Maschine, after installing Creators update. It was both as standalones and plugin versions, and in multiple hosts, not just Sonar. Standalone versions wouldn't open, attempting to add them as plugins would crash the host. Updating my GPU drivers fixed it. Seemed random, but it worked.

There is also a new restriction on driver installation unless they have a Microsoft certified digital signature they now won't install properly.
This explains the workaround https://www.howtogeek.com/167723/how-to-disable-driver-signature-verification-on-64-bit-windows-8.1-so-that-you-can-install-unsigned-drivers/
 

My XLN plugins showed that they weren't registered. Apparently it thinks its a new computer now. I re-registered my computer using the XLN Registration program and it's all fine now. So far my other plugins seem to load fine.