I'm also having those timing issues with JP and reverted back to the previous version. 
The problem seemed to be worse with higher latency settings, although that could be a coincidence. 
I also tried increasing the midi buffers, but that didn't help.  

Danny Danzi

Fabio Rubato

stlstudio
After updating to Jamaica I noticed I was missing waves plugins in my vst3 directory so I did a rescan & got a hang on a waves plug also. So I rescanned again only this time I unchecked "rescan failed plugins"/rescanned/and all my waves plugins scanned correctly.

Okay, thanks for that. I could try that, but I'm not sure at this point whether it's going to fix the issue with a number of VST softsynths that are starting late and continuing to play once the project has stopped. I've installed Jamaica and un-installed around 4 times now, so I'm going to wait until tech support contacts me, which will probably be 2 weeks done the line, based on past experience. 
 
Again, thanks for that. I assume you're not getting any weird timing delays with your soft synths?

Fabio, in your options, midi/playback and recording, what is your playback set to? Default for playback is 250...if you have yours set to that, what happens if you try 500, 800, 1000 or even 2000?
 
One of my machines is set to 800 as I had some drop outs using hardware synths years ago, so I never touched them. The other two were 1000 and 2000. Those numbers just seemed to work where I never had an issue with anything.
 
On one of my machines, setting that option to 500 sort of cured my synth problem to where it will work great for the duration of the project being open. As soon as the project closes and I close Sonar and reopen, the sync issue is back...but all I have to do is start/stop playback and the sync issue is gone again.
 
That said, on my other two machines....I am unable to make it stop no matter what I try. I'll keep looking into this and let you know if I figure anything out. I'm going to try and contact Cakewalk to see if they know anything also.
 
-Danny

 Hi Danny...I usually set it to 500 which seems to stop any playback dropouts. I could try some of the other settings you mentioned. This is Cakewalks' suggestions:
Thanks for your reply. Regarding the Waves plug-in, is it the most current version? This may help: try scanning with "Rescan failed plug-ins" unchecked, or temporarily remove the WaveShell plug-in from the plug-in scan path, then doing a reset/rescan to bring in everything else in. Then, bring the WaveShell back into the VST folder and re-scan. Does the scanner still get stuck?
I'd also like to find out: which version of Windows are you using?
We've heard of some specific latency issues with the Jamaica Plain update, but I'm not convinced this is the same thing. Do you happen to have your project set up with any sends on your synth tracks? If so, try temporarily removing them and see if that makes any difference. 
Try switching driver modes in Preferences (Edit>Preferences) under Audio|Playback and Recording, and see if you are getting the same latency in MME (32-bit) with the RME device. In MME (32-bit), you can also try testing your computer's built-in sound card, if it's enabled, to see if the same latency occurs there. This will let us know if it's specific to your audio hardware.
Please let me know what you find!
 
So there's a few things to try...I keep having to rollback to Ipswich so that I can work with my projects, so testing is minimal...but I'll give these suggestions a go today and report back.

I noticed that some people with timing issues use a RME sound-card. I'm using a RME UCX. 
 
So I'm curious, does everyone with this problem use a RME card? 

Me too. With AD2. With projects pre-Jamaica.
 
Will suddenly just skip a beat, in either Playback or Record, and it's random. Or the midi track will just start a second out of sync with audio tracks and remain that way. Tracking has to be broken up into 30sec or less sessions. Been chasing the problem for the last week. Should of just had a look on the Forum!!.
 
Also, I'm having tempo issues, or it's just slowing down, for a second or two, then goes back to the right tempo. It's not a tempo change, just something dragging the system down. Also, initial playback/record, the start speed may vary. My PC is not online and runs nothing but Sonar. If I save, close and exit, reboot, come back in, it will work OK again for maybe 20 takes, and then it all starts again. This all started with Jamaica.
 
I will roll back for the time being, and read back through this thread and other related threads to see what I can try.
 
cheers Dave.

liinnerd
I noticed that some people with timing issues use a RME sound-card. I'm using a RME UCX. 
 
So I'm curious, does everyone with this problem use a RME card? 

I am using a non-RME card; this issue does not seem to be depending on the type of the soundcard. Did a rollback, after that everything worked again correctly. I am waiting for the next update/hotfix for Sonar...