iZotope Stutter Edit loads by default as a VST audio effect.
 
I click on the properties in the plug-in manager and select it to be configured as a synth.
 
On the next re-scan, the VST2 version appears as a VST instrument.
But the VST3 version stays on the Audio menu in the browser.
If I load the VST3 and check it's properties, it is still marked as a synth and it works fine.
 
In the plug-in manager, the reverse happens - Stutter Edit stays in the VST2 audio folder, but for VST3 it moves to the instrument folder. This is rather bizarre.
 
So this is really not much of a problem, since it works properly, but shouldn't VST2 and 3 work the same way as far as plug-in menu behavior goes?
 
iZotope VocalSynth behaves the same way - works properly as a synth, but the menu display is wonky.

I reported this some time ago. IIRC, the problem starts with the way VST3 inventory records are built. The flag is set in the wrong record (or not completely set depending on how you look at it). I believe this is one motivation for Cakewalk adding the MIDI I/O enable options to the VST drop down in the standard header. This happened at the same time as VST3 support in X3. Using the drop down achieves the goal of exposing the plug-in to MIDI data albetit a per-instance per-session setting.
 
As an aside, it is my understanding the iZotope VST3 plug-ins are VST3 in name only. They implement the barest part of the spec to load as VST3 plug-ins.

As an aside, is there any particular reason why you're configuring Stutter Edit as a synth? I use it as an effect and it works great like that....

Yes, it does work just fine using the drop down, however; given the plug-in would rarely be used without MIDI input, setting as a synth saves the config step for each session instance. The plug-in is not unique in that regard. It would be handy to have control over VST3 plug-ins like there is with VST2. Maybe the upcoming browser updates will address this and some of the other quirks in plug-in management.
 

sharke
As an aside, is there any particular reason why you're configuring Stutter Edit as a synth? I use it as an effect and it works great like that....

To get MIDI input. This was the older way to do it. Now that we have the MIDI menu on the VST header I guess this isn't necessary.