So after 3 days of reinstalling stuff, I think I'm down to my last issue.
 
I installed UVI Falcon, the .dll is in my vsts folder, but it doesn't show up in Sonar Platinum. Can't figure out why. It runs in standalone fine. I also have UVI Workstation and that shows up in Sonar. Falcon used to show up on my old setup. It's just not there when I go to plugin manager. The folder that the .dll is in is definitely being scanned (it's in my main /program files/cakewalk/vst plugins folder).
 
Any ideas?

Check the VSTi/VST3i excluded lists. If it is in there, enable it.

Thanks Scook but yep, checked in there too. So weird.

They may have failed on scan. If they work after being enabled you are good to go. If not they need to be scanned again.
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Probably misread your reply.
You can create a scan log by holding the SHIFT key while clicking the scan button in Preferences. This may give you some info. VST reset is an option too.

Some plug-ins need to re-register through their installer. So my guessing would be you just need to reinstate the plug-in again to ensure it's working as expected. Weirdly enough, I never had to reinstall any plug-ins last time. Well a couple of Sonar things like Drum Replacer and Engineering FX.
 

If it failed a previous scan it may have gotten marked as bad - if so then it will be ignored in future scans unless you go into the VST Settings and check 'Scan Failed Plug-ins" box before next scan. 
Don't remember if the box unchecks itself after the next scan so check back and uncheck it if it doesn't.

polarbear
So after 3 days of reinstalling stuff, I think I'm down to my last issue.
 
I installed UVI Falcon, the .dll is in my vsts folder, but it doesn't show up in Sonar Platinum. Can't figure out why. It runs in standalone fine. I also have UVI Workstation and that shows up in Sonar. Falcon used to show up on my old setup. It's just not there when I go to plugin manager. The folder that the .dll is in is definitely being scanned (it's in my main /program files/cakewalk/vst plugins folder).
 
Any ideas?

Try simply to cut past it on a place not scanned ..scann again , it will unregister it from registry , then close sonar , put it back and rescan ...it done the truick for me several time

removing the file from the vstplugins folder, rescanning, then putting the file back in the vstplugins folder and scanning again made it work! thank you Zo.