This is more or less a random effect. I haven't figured a 100% repeatable recipe, but this is how far I got:
 
1. Create new project (Blank, no name will do)
2. Add an audio track
3. Record a few seconds - silence will do.
4. Add a master bus and put the new multiband compressor in the effects bin. Add a band or two.
5. Assign the output of the audio track to the master bus.
 
Here's where the messing around starts.
Close the multiband compressor and re-open it by clicking on the middle of the bar in the FX bin.
Start Play in the transport controls. If the Stop button lights up, the fault hasn't happened, so stop the transport, click around and change some values in the MB compressor, possibly close and re-open it, then start play again.
 
After some messing around, I find the Stop button stays de-activated. Clicking on it will not stop play. Only closing the MB compressor will activate the stop button, allowing me to stop play.
 
Anyone able to reproduce this behavior?
 
Sometimes it happens the first time you try, usually it takes some patience.
 
I also notice sometimes the Stop button DOES activate, but with a bit of a hesitation.

This happens to me all the time now. In my case, not just since the two new plugins. Since one of the Platinum releases during 2015. I've commented on it previously but until now I've not seen anyone else express this scenario is happening to them.

In my case I can add a VST of just about any flavor and after doing some tweaks on it after a certain amount of actions the Stop on the transport gets grey and the now time just keeps playing.

I can save my file, quit Sonar, reopen my file and everything is fine. Rinse and repeat.

This happens to me so often I've just become accustomed to it as my new norm.

I've happily accepted sending my analytics to the Cakewalk team (with this new release) in the hopes they'll see a ridiculous spike in this error situation from my feed to their analysis.

Really? Interesting.
I did try the old 5-band MB and was unable to reproduce the effect.
Perhaps I didn't try often enough. I'll give it another go.
 
I am also getting the sluggish effect mentioned in another thread - the Now cursor stumbling along and appearing as double lines. I'll try again with Linear Phase off.
 
I have a Win7/64bit i7 12GB RAM laptop, dedicated to DAW only (no antivirus, no WiFi, etc) so it's not a slow machine.

jpetersen
 
I have a Win7/64bit i7 12GB RAM laptop, dedicated to DAW only (no antivirus, no WiFi, etc) so it's not a slow machine.

Is this machine using ASIO4All instead of a vendor written audio driver? If so, it may not matter how much computing power the machine has.

No.
This is my studio machine and only uses the ASIO drivers supplied with my Cakewalk UA-25EX interface.
 
I also have an old small Atom-powered XP netbook for recording bands in their rehearsal rooms.
That has Sonar 8.5.3 and uses ASIO4All.

graphics driver up to date?

Everything up-to-date.

I am experiencing a lag time in response on all transport controls when using the new LP plugs.  

TPayton
I am experiencing a lag time in response on all transport controls when using the new LP plugs.  

This is to be expected if they're operating in Linear Phase mode. There is an option in the plugin window under the Expert button to switch the precision to non linear.
Try this to improve the latency

jpetersen
No.
This is my studio machine and only uses the ASIO drivers supplied with my Cakewalk UA-25EX interface.

 
It seems you have a lot of "one off" bugs that others have not been able to reproduce. I wonder if this means something in your system is problematic.