Can someone see if they can reproduce the issue below:
 
Open Sonar Plat with a blank project.
Put RP Delay in a FX bin by dragging it over from the plugin list
With the GUI of RP Delay open, drag any other RP effect across the GUI of RP Delay over to the FX bin.
 
I get a crash every time with any combination of any two RP effect plugins.  All are on the latest versions.  
 
If I close the GUI of RP Delay before dragging the other effect over, it works fine.  
 
What might be causing it?

I don't have the plug-ins to test. Do you have plug-in window recycling enabled in Preferences > File > VST Settings? If so, disable it and see if the there is still a problem.

scook
I don't have the plug-ins to test. Do you have plug-in window recycling enabled in Preferences > File > VST Settings? If so, disable it and see if the there is still a problem.

I unchecked it, but I still get the same problem.  The Sonar window says it's an unhandled exception.
 
I appreciate the suggestion.