As well as a couple of Waves plugins that I use a lot (Q10 and SSL E-channel), I now have Ozone Imager losing its settings on a regular basis. I save the project with the widening feature turned on, yet the project sometimes loads with it turned off. 
 
I was just thinking about this today and had this whimsical hunch that perhaps it has something to do with the plugins being configured as a tempo based effect? All my plugins seem to be by default, yet I figure most of them don't actually need to be. Perhaps with this option checked, Sonar is communicating sending the plugins information about song position and tempo, and this information is somehow ending up in the wrong place and causing settings to be messed with? 
 
Anyway I'm gonna turn it off and see if it makes a difference. 

I too have had have had this occasional issue for years James, with various plugins, mostly vsti's. Damned if I can find any rhyme or reason to it's occurunce! I remember it started with a release that caused it to happen with all VSTi's that Cakewalk released a fix for almost immediately, but it has lingered on a semingly random basis. It seems to hide long enough for me to forget about it until I am working on a project that I have spent hours tweaking sounds in:)

It's been a big problem for me going back to 2012 or 2013 or so. Started off with Native Instruments synths and Waves plugins. Reaktor was one of the worst offenders. I'd load projects with every Reaktor synth flatlined and God knows how much work I lost because of it. Then they fixed all that and I was a happy camper. At some point, the Quadcurve EQ developed a problem (also reported by others) in which you'd load a project and every instance of it in every ProChannel would have these insane 16dB cuts or boosts at the same frequency. It destroyed my mixes dozens of times. At some point, that problem seemed to go away too and I was happy. But over the last few months it's come back with a vengeance with the Waves plugins, and once again I've had entire mixes go to pot because of it. 
 
I have a huge project I'm working on now with 100+ tracks and almost all of them have the Q10 on them - I had to save presets for all of them and every time I load the project I have to go through all of those tracks, see which ones Sonar has flatlined, and load the preset. Unbelievably annoying and time consuming. 

I hear you. It is extraordinarily frustrating. I can't believe more people haven't run into it. I used to think it was mainly Kontakt and waves plugins that it happened in, but it has pretty much popped up in everything I use over the years. Nothing worse than opening an archived project to find all of your sounds gone!
There are many things I will miss from Sonar. This certainly isn't one of them.

I see this phenomenon on a regular basis, but always with the same plugin: D16 Group's Redopter. The frequency with which I see this may simply be due to the frequency with which I use that plugin, which is at least 50% of my projects. I deal with this by always saving a preset named for the song and track I'm using Redopter in, so that it's easy to restore. Still a PIA.
 
I have not seen the issue with any of the iZotope products. However, I don't ever use the standalone Imager. I only ever use it as a component of the Ozone main UI.
 
This has got to do with the way settings are persisted. They're either not being saved with the project save, or not being restored on project load. Unfortunately, I do not understand how that works in SONAR. Obviously, the information must be saved with the project file, but that file format is proprietary and undocumented and therefore opaque.
 
I do know that there is a protocol - part of the VST spec - for hosts getting and setting plugin parameters. That protocol changed between VST2 and VST3. Since iZotope installs the VST3 versions by default, you might try replacing them with their VST2 equivalents to see if that solves the problem. That's just a wild guess, though; in my case the D16 plugin is already VST2.
 
I just noticed that here the standalone Imager is VST2, while Ozone is VST3.

I recently ran into this with a couple of no-longer-supported 32 bit MHC VSTi's.  And then discovered that, although they used to work (as I'd used them reliably under 8.5.x, if I remember rightly), they no longer saved state in *any* VST host I tried them in - since they've had no updates for years, I assume that a Windows update (I'm on 7 still...thankfully!) broke their persistence in some way.  Not expected at all, but maybe worth checking these on another system (ie. different set of Windows updates) or in a different host on your machine.

I've seen this happen with the Adaptive Limiter.
 
Paul

Interesting to hear other people report this now, I did feel like I was somehow doing something wrong or was cursed, judging by how few people mentioned in on the forums before. Maybe we should have kicked up a bigger stink about it, lol! 
 
As a beta tester it was a constant source of frustration that I couldn't come up with a recipe to recreate the problem. And it seemed so random - sometimes these synths and plugins would load fine, other times they would load flatlined. Someone else on the beta team with the Quadcurve problem said they think they saw it happen after moving the playhead in a project, so that might have been a clue. 
 
As for the Waves issue, I did find a promising clue not long before Cakewalk went kaput. I was able to capture on video a band of the Q10 moving without touching it, along with a recipe of how to recreate it. Check this out: 
 

 
I discovered it quite by accident. I'd opened the Q10 to make an adjustment, and after wondering why I couldn't hear any change in the audio, I saw that the ProChannel that the Q10 was hosted in was turned off. When I turned it back on, the band I'd adjusted moved on its own. I think the same thing happens with FX bins as well. So there you have it - an illustration of how turning on a ProChannel (after having made an adjustment to the plugin with the PC turned off) can send a signal to a plugin and change its settings. 
 
So that got me to thinking about how these plugins were being changed. I don't think it's that Sonar is not saving the settings in the project file - I think it's more likely to be that something is happening as the project loads. Could it be that as Sonar initializes your ProChannels or FX bins, these stray messages (whatever they are) kill or vandalize plugin settings? And maybe something along those lines is happening when synths are initialized in the synth rack as well? Or maybe that's not the case at all, and the problem in the video is totally separate!
 
I submitted the above as a bug, and the Bakers were able to reproduce it. And then Cakewalk was no more. Daaaaamn......

I get this often too, seems to be pro channel related. I find the concrete limiter can often mess things up for me. I might have to try just using the FX bin and not use the PC anymore, pitty cus I love the PC EQ. 

Rasure
I get this often too, seems to be pro channel related. I find the concrete limiter can often mess things up for me. I might have to try just using the FX bin and not use the PC anymore, pitty cus I love the PC EQ. 

The problem illustrated in the video above happens with the FX bin as well, so I think both are problematic. I bet the FX bins and ProChannels share a certain amount of code.