is your Windows install using English or something else as its default language?
This may be related to a slight change in the behaviour of the speech recognition engine where the old SRE used the installed language pack as its default language, but the built-in SRE uses the windows UI language setting as its default language. We're explicitly setting our grammar objects to en-GB, but relying on the recogniser matching this by default, which might not be the case any more.
If you change that property value I suggested in my previous post it might fix it until I get another hotfix build out (but, like before, I'm having to guess at the problem as I can't reproduce it)