The VST Adapter is not providing full channel routing information for VST plug-ins. In the case of the EasyVerb (which is a true stereo reverb) this may produce this kind of problems depending on chosen algorithm. Please use any other mono-stereo plug-in before the EasyVerb to get a proper input signals for the EasyVerb.
Regards,
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Mateusz Wozniak
PSPaudioware.com