lawp
my speculation is that the synths with issues are trying to utilise some as-yet-unimplemented-in-sonar part of the vst3 spec, whereas the other hosts have implemented that, and that sonar's vst3 implementation will continue, and that with some future sonar update these synths will work, but that's just speculation

I would say this - if you've ever dealt with standards documents you find that sometimes they are very specific, but at other times they are quite vague on just exactly how some things are supposed to be implemented and work.
 
So sometimes you end up with different vendors interpreting and implementing things differently.

Can confirm

If an effect or instrument ships with both VST2 and VST3 versions, why on earth would you want to use the VST3 version (if you're not a Cubase user)? Is it the ability to save preset names in Chinese?

Waves told me they only support VST3 now, not VST2...

bitflipper
If an effect or instrument ships with both VST2 and VST3 versions, why on earth would you want to use the VST3 version (if you're not a Cubase user)? Is it the ability to save preset names in Chinese?

这就是为什么我这样做！

bitflipper
If an effect or instrument ships with both VST2 and VST3 versions, why on earth would you want to use the VST3 version (if you're not a Cubase user)? Is it the ability to save preset names in Chinese?

Well, it's one better, isn't it? It's not two. You see, most blokes, you know, will be playing at two. You're on two here, all the way up, all the way up, all the way up, you're on two on your VST. Where can you go from there? Where? - This one goes to three!
There are a few potential features that could be added in VST3 but I seriously doubt if Sampletank 3 or the Arturia instruments that caused me problems use any of them.
 

drewfx1
I would say this - if you've ever dealt with standards documents you find that sometimes they are very specific, but at other times they are quite vague on just exactly how some things are supposed to be implemented and work.
 
So sometimes you end up with different vendors interpreting and implementing things differently.

^^^ This. VST3 has been around for a while, but it's only starting to get traction now and that's bringing issues to the forefront. Also bear in mind that much of VST3 is future-oriented, and that manufacturers can choose which features to implement.

bitflipper
If an effect or instrument ships with both VST2 and VST3 versions, why on earth would you want to use the VST3 version (if you're not a Cubase user)? Is it the ability to save preset names in Chinese?

Well, if the plug-in AND the host implement the "only draws CPU power when actually doing stuff" feature, that would be useful. But I don't know how common that is yet.

Just for everyone's information ...
 
IK Multimedia have released v3.01 of SampleTank 3 in the "user area" of the website.
It has unfortunately not fixed my issues with "stuck" notes etc.  But maybe this release will fix a couple of other issues people are having ... YMMV.

Here is the list of changes made in the 3.0.1 update; hopefully you guys can report back if this fix, helps with the issues with Sonar and ST3.  Here is the list of changes:

Changes from version 3.0:

▪ Fixed issue with Big Pig pedal
▪ Fixed possible crash opening Settings Dialog in StandAlone version with a non-available Device selected
▪ Fixed possible crash opening Settings Dialog in StandAlone version with a non-available Device selected
▪ Fixed possible crash on startup with some ASIO Drivers
▪ Fixed crash on drive missing for ST3 Disk Path
▪ Effects Presets folder moved inside the Disk Path
▪ All content folders are now created automatically if they do not exist
▪ Fixed a bug that made MIDI CC assigned to element and zone parameters to not save and restore correctly
▪ Fixed a bug that when importing samples, made data from editable fields not reflecting the latest user input
▪ Fixed possible "boost::filesystem::remove" error while importing legacy instruments
▪ Fixed a possible mismatch between macros description in the info panel and macros enabled/disabled in the macro panel after loading legacy instruments
▪ Fixed Import of modulations from legacy instruments contained in the Xpansion Tank Vocal library
▪ Fixed possible BPM SYNC issues with certain hosts
▪ Fixed a bug when importing some kind of WAV files
▪ Fixed a possible issue when writing automation parameters on certain hosts