I am pretty sure you did something wrong,
you should not use that way on Sysinternals_Suite anyway, I wrote above for your standalone plugin following the way you suggest ...
personally, better not to use [Variables] for %PluginArch% .....
"Sysinternals Process Monitor"
plugins change this section:
//to run procmon.exe on hostx64 both fltlib.dll required...
// Thanks, dera!
Let us know it is all ok now