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.

Regards
Vic