There is an bug with the scan process which is becoming quite annoying as a whole load of pre-sets are not being seen.
If an error occurs for example it doesn't like a plug and gives you the option to "Enable Risky" or "Enable" whatever you choose the scan stops at that point and misses anything else further down the list.
 
I am sure that in earlier versions (Current 2017-01) this did not occur.

If you feel the issue is release related, the first thing to try is roll back to the version you were running before.
 
You may be over scanning plug-ins. The only conditions which cause plug-ins to be rescanned are running a reset, when the rescan failed/existing options are checked or when plug-ins are updated. Other than updates the other conditions are special. As a rule the rescan options should not be enabled.
 
The errors you are seeing may be the result of something that occurred before the scanner attempted to load the plug-in displayed in the dialog. This could be the result of attempts to load binaries that not VST2 plug-ins. This is often caused by a bad scan path. It could also be a bad interactions between some plug-ins and the scanner.
 
 
 

Just a few more things.
 
It may be helpful to know which plug-in is mentioned in the error.
 
At some point, you may want to create a scan log. This is done by holding the shift key when clicking the scan button in Preferences > File > VST Settings.