Many moons ago there were some issues with Waves plugins specific to Sonar - namely, that some of their GUI's would not play nice. Supertap, for example, had horrible controls which would "spring back" when you set them. Both companies recognized the problem and if I remember rightly, they were in contact with each other to come up with a fix. 
 
Recently I've been experiencing similar issues with laggy/jerky control knobs, clicks and pops (in their Element 2 synth, even when my overall CPU activity is moderate) and I have just discovered this morning that Sonar has been nuking all of my SSL E-Channel settings back to default in a project. 
 
So I was wondering if these issues were being experienced by others, if so I would draw it to Cakewalk's attention (and maybe Waves too) so we can see about maybe getting them sorted out. 
 
 

Are you using the VST2 or VST3 versions? Which update of waves are you on?

Other than issues with Waves Central, I have not run into any...
 
Regards,
Dan

Hi. I have not had any issues with any of the Waves plugins / synths lately. I'm only using the Vst 3 versions.
All the best.

Lance Riley [Cakewalk]
Are you using the VST2 or VST3 versions? Which update of waves are you on?

The version of Element I'm running is 9.91.0.7 - as far as I know, all of my Waves plugins are up to date (leastways, whenever I install a new one it seems to do a fresh install of all the others). I'm using the VST3 versions. 

No problems here either (so far).  Just created a quick project with a Waves SSL E Channel on a bus.  The saved plugin settings were the same after restarting SONAR.  I'm running Platinum 2017.05 on Win7, Waves SSL Channel is rev 9.91.0.445, VST3. 

No Problems with any of the Waves Plugin in Sonar Splat as of the 2017/06 update

Thanks for checking. I had a similar problem with Native Instruments plugins a few years ago wherein Sonar was nuking all of their settings back to the defaults when loading projects. Very few people were reporting the same thing on the forum, but those problems were largely identified by Cakewalk and fixed. I also had a horrible problem for ages with Sonar making all of my Quadcurve EQ's go crazy by enabling 16dB cuts and boosts all over the place - again, very few people experienced it (although a couple of others did). I have a feeling that somewhere along the line, stray MIDI signals are finding their way to plugin parameters. I also have some pretty bad problems with MIDI leakage from time to time, so something is clearly astray MIDI wise. My projects are largely MIDI based and I have a lot of routing going on, so maybe that's why I'm seeing it more than others. 

James I tried the Element Synth today as a standalone and as a vst. (Man that thing sounds great!)
 
Did not experience any lag at all. Tried some pads and some arp stuff, played around with the Occilators, LFO, VCA filters all while I was playing it and didn't see any lag.
 
However, I was working on another project that has Waves H-Delay in it and I couldn't get the mix knob (on the delay) to record any automation using the "W" to write automation. 

All my Waves plugins show except for the SSL Channels. They are installed and the .dll's are there. I followed the waves instructions for a manual scan and that didnt work either.