What Visual Studio and Visual Assist versions are you using?
I wasn't able to reproduce your problem so far, using VS2010 and VS1859. Something is triggering the problem for you but it may not be the formatting. "Move implementation to Source" wasn't grayed out for me using the following code:
class Polypoint
{
Polypoint(float* verticles)
:
Renderable(PT_POLYPOINTS)
{
}
};
Can you please try creating a clean new win32 project and try whether the above sample triggers the problem for you?