headphone monitoring

There is a plug-in called “TB_IsoneSurround” issued by ToneBoosters http://www.toneboosters.com/free/.
It seems to be helpful in headphone monitoring and is free (also 64-bit version). When I load it into the master section slot (either pre or post faders) during audio being played it works fine, but when I it’s loaded before I push play button it makes master section stuck and no audio can be heard.
Is this plug-in’s fault or WL’s?
Anyhow it would be great to see such feature built at the end of monitoring chain but not being included into the rendering process of course.