With the fix.

This is my post last night explaining my project and how stable things appeared to be:-

http://forum.cakewalk.com/fb.ashx?m=2676778

and this is a more recent post where another user was experiencing an issue with Build 308 and I was able to emulate that issue:-

http://forum.cakewalk.com/fb.ashx?m=2677317

Thanks for your report. We'll investigate it next week but I feel pretty sure that what you are seeing is unrelated to the quickfix. From your notes in the other thread, you are seeing it only while moving RMix right? The only fix to RMix in the update had to do with a problem when switching to higher sample rates. 
Send me a pm with your email address and the CWBRN you logged we can follow up next week and try and narrow down your issue further if you still have the problem.

When I put R-Mix in a track it opens up and thats it.....I can see it but can't use it like it is frozen. It also causes audio engine to stop....and dropouts

 I did some tests with no fix applied. Open the mixing cwb included as part of the download. Added breverb, console bus and track console plus put rmix on every track. Working 100% . No issue switching between console view either no crashes. 
Windows 64 bit X2 64 bit HP Probook 4530s asio4all drivers.