Cantai’s v3.0.2 release today seems to have addressed a number of issues. One might want to install it and give previously rendered works a try with the new processing. I’ve found several things that are working much better.
I’m running the latest versions of Dorico Pro and Cantai on Windows 11, and unfortunately, there’s been no improvement in how projects close. All four Cantai (SATB) windows stay open, as does the mixer. Dorico’s main window disappears, but any attempt to interact with what remains (the mixer) causes Dorico to crash (or confirms it already has). Task Manager shows that VSTAudioEngine (hosting the four Cantai instances) is “Not Responding.”
In terms of a successful project shutdown, these are the steps that seem to work: save, close mixer or other Dorico windows, close Cantai windows.
I used Revo Uninstaller Pro to completely uninstall and sweep up all remnants of the previous Cantai version before installing 3.0.2. Beyond the closing issue, Cantai’s performance has improved noticeably: it now utilizes my RTX 3070 GPU for much faster rendering, along with numerous other audio and quality-of-life enhancements. In the end, 3.0.2 is a mixed bag of great and not-so-good!
Is this any different than the 3.02 Beta? (If so, I would think that they would update the version number!) 
One would expect the release to be higher than the beta but so far it appears to be the beta plus additional improvements. I am experiencing higher quality sound and better dynamics. My understanding of the beta was that it was just addressing GPU processing.
Who knows anything for certain with Cantai? Much of this product has been smoke and mirrors in my opinion so I’ve just decided to go with the flow. I keep every version of the installer (so far) so that I can go backwards if the need arises. It does get “tired” when the cache exceeds 8G as far as I can tell resulting in sloppy pitches. Deleting the cache for all (now there are delete options for the cache) seems to fix the issue.
Not necessarily. In software, 3.0.2-beta is generally just a prerelease version of 3.0.2, not a precursor to 3.0.3. So you might see 3.0.2-b1, 3.0.2-b2, and then the released 3.0.2 – and each of those might include some changes.
There’s often a fourth component to the version number, a build number, that does get incremented each time but that is usually only relevant for people like devs and beta testers. For example, Dorico has:
And Windows has:
The latest version included improvement keeping voices in sync where they would falter rhythmically in former versions. 