I usually wait several months before upgrading to any new Sonar release, just to make sure that most of the bugs have been worked out. However, after seeing the videos of X3's new features, I was completing an X2 project, wishing I had those new features...and I decided to jump into X3. I love it!
 
Sonar has taken a huge leap ahead. I especially enjoy Comping, Color Customization, the QuadCurve Zoom & Analyzer and X3's integrated way of handling Melodyne. As a long-time user of Melodyne Editor, Sonar didn't always play nice with Melodyne, but now they're best friends.
 
Unfortunately, my installation of Sonar X3b has major problems with my UAD-2 Quad system, and they're not exactly like what has been described elsewhere on the Cakewalk Forum.
 
For example, I can insert an instance any UAD-2 plug-in all by itself into a track or bus and the GUI will open up, but the plug-in receives no input and there is no audible difference when switching the plug-in on and off with UAD's power switch on the GUI. However, when I switch the plug-in off-and-on using the button to the left where the plug-in is listed in Sonar's FX bin, it begins to respond and I can hear its effect on the audio. This works only if I switch off-and-on in the bin while tracks are playing. Then, when I stop the transport and hit play, the plug-in quits working again. 
 
I must also note that, when a UAD plug-in is inserted all by itself into an individual track (rather than a bus), when I successfully achieve processing via the on-and-off method described above, that particular track becomes slightly delayed and out-of-sync with everything else. I have seen this mentioned as being a problem when used in the bin with a VST3 plug-in, but I am having this problem with UAD as the ONLY plug-in.
 
I am running UAD-2 software version 7.2.0 08-05-2013 build 3900. I've seen discussion of the new 7.3 update online, but according to the documentation, it doesn't cover any Sonar issues.
 
I reported this problem to Cakewalk tech support last Wednesday, with no response since then, other than an automated acknowledgement of receipt. I submitted the problem to Universal Audio at the same time, but discovered today that they had not received the submission, so I tried it again.
 
Any input from those with both X3b and UAD-2 would be appreciated.
 

I have some big issues with my UAD 2 plugins also . X2d had no problems , But with X3 , I get the bothersome UAD Latency warnings every time I move or insert a plugin. I found that the UAD 2 plugins will work in the regular fx bins on the channel BUT THE PRO CHANNEL FX CHAIN MODULE MESSES UP BAD , They will just stop working when I open a project. The Ampex Tape machine plugin will have massive latency when the project is first opened , The bypass trick will work to get it tight again But the Studer seems to be fine . So my work around to start using X3 with UAD was to #1 tolerate the UAD latency messages #2 never use the Pro Channel for UAD #3 stop using the Ampex Tape plugin . Now I'm working in X3 Smoothly now but wish I had my stablity back for the UAD 2 stuff.  X3 is Super cool 

Could it be issues with using bit bridged 32 bit plugins in a 64 bit project?

This isn't good news.. =( I hope they fix it... But the UAD plugins are now 64 bit...  so that shouldn't be an issue with the bitbridge and latency anymore.

The only time I get the latency warning is if I do something like this (in the FX bin)
 
UAD plug
non-UAD plug
UAD plug
 
I have not tried to insert UAD into an FX Chain but I will tonight or tomorrow.
 
I am on version 7.1 of the UAD software.

Due to past 32 bit/64 bit problems, I stick exclusively with 64 bit plug-in's. To double-check, I just began a Sonar X3 project with no plug-in's in any bins, except for 1 UAD plug-in on a single track. I got exactly the same result as described in my originial post. And, unlike bobgassert, I never get a UAD latency warning.

So far I've had the latency message issue as well meters not working on the precision limiter and on the Shadow Hills MC. The plugins seem to be working otherwise.

Boo. Pulled the trigger yesterday because I thought the UAD stuff was in the tolerable range but I guess I'll have to wait to dig in til they update the plugins or CW figures out what's up. Usually this stuff gets sorted out by the next UAD update following a major release from cakewalk.

I'm seeing the same thing with X3b and UAD v7.3 (muted plug ins).  I'll try to recreate and submit to Cakewalk and UAD if I can.
 
Cheers,
 
jayson

I am having similar glitches with my UAD plugins. Make sure to submit a support ticket to UAD directly on their site - these issues will not get fixed in a timely fashion until numerous users start making noise.