Sampletank 3 crashing Sonar Platinum 2017.06 for projects created with earlier version

Did you try the VST3 version or the VST2 version? Try the VST version of sampletank, if you installed the VST2 and visa versa
 
CJ

I have posted c. 1000 crashes related to Sample Tank3. It does not matter VST2 or VST3, older Sonar update or most current - I got crashes having only one instance with one instrument, say bass. It is enough to do some playing on my midi keyboard to get a crash accompanied with high pith buzz. ST3 is great and I obviously love Sonar too, simply HOPE ONE DAY BAKERS AND IK MULTIMEDIA PEOPLE WOULD GET TOGETHER TO SORT IT OUT.

I don't think Cakewalk actually looks at crashes submitted until it comes up with a support case.  So I doubt anyone even noticed you sent it.
 
Sampletank's VST3 implementation has always been very buggy, especially with loading/saving projects.  So much so I've removed it.  Note that old projects saved using the VST3 version will continue to load the VST3 plugin if all you do is disable it in the Plugin Manager.  The only way to stop it from using the VST3 version is to remove the plugin itself from your VST3 directory.
 
If I were having these crashing problems I'd do the following things. First turn off the "Hide Related VST2" Plug-ins and "Replace if Possible On Project Load" options under SONAR's Preferences->File->VST Settings.  In fact that replace if possible option might be the real problem if your older projects used the VST2 version.  The Hide option is mostly because I prefer to see both VST2 and VST3 versions of plugins (so I have control) but it might be painful for you.  Not sure what the right answer is for that one.  The Replace option I don't think is a very good thing since plugin developers aren't so careful about project compatibility.
 
Then load each old project and inside Sampletank go to the Multi panel and use the Save As option to save as a ST3 Multi (*.st3m).  That way you can load the settings into the VST2 version.
 
After I had saved out all the project settings.  I'd close all the projects and go into the Cakewalk plugin manager and disable the VST3 version of Sampletank.  Then I'd exit the Plugin mangaer and then exit SONAR (I don't recommend running the plugin manager without SONAR being open/staying open).  Then I'd remove the Sampletank3 VST3 file from C:\Program Files\Common Files\VST3\SampleTank 3.vst3 (move it somewhere else).
 
Then I'd load the bad projects, most likely they will give an error about missing plugin.  I'd then replace the bad Sampletank3 with the VST2 Sampletank3 (I'd try replace synth in the synth panel but if that doesn't work use the kill and re-add completely method) and re-load the saved Multi. Then resave the project under a new name.
 
Sadly I'm not really sure though that will fix your problems, some people claim to have never had problems with the VST3 versions of IK plugins.  I do know the VST3 version of Sampletank3 has caused lots of crashes that the VST2 version doesn't seem to do.  I have the crash dumps and more than enough skill to use a debugger to tell what crashed.  It's always the VST3 version of Sampletank.
 
When you open the Sampletank3 plugin UI, at the top of the plugin window SONAR shows options on the plugin including a drop down that shows if it is the VST2 or VST3 version of the plugin you are running.  If you open a project and it says VST3 you know you didn't get the removal of VST3 stuff right.  (This is how I know SONAR will use the VST3 version if all you do is disable the plugin).

I wish I was sure any of this will help your problem, sadly there isn't really any magic bullet. Bugs in VSTs are like that.  Unless the developer can reproduce it on command and is willing to look at and fix it, the best you can do is try and find ways around it.  And save often.
 
I've seen enough reports from other DAW with issues with Sampletank's VST3 plugins to make me suspect that when I see crashes with Sampletank involved.  But your problem may be more involved.  I'll admit I haven't been using Sampletank much this year, so it's possible SONAR has developed new problems. 
 
I'm fairly certain they will be shipping a new update to Sampletank this month though, to support the new features needed for Syntronik.  The last Sampletank update shipped in Dec of last year (3.6.7).  It's possible the new version will handle things better.  I know I'll be updating as soon as it ships.  But I don't think I will even bother with the VST3 version this time.  In the past I'd "try" new releases in VST3 form but I always regretted it.
 
Good Luck.