analogika

It's - AI stem separation - Auto Bass (AI?) - Auto Keys (AI?) - Studio keys - studio bass - ChromaGlow AI-based simulation of all sorts of interesting analog artefacting (we'll see what this is), not just in the master channel strip. - integrated Dolby Atmos That's not really that minor, and I assume it's chock-full of new frameworks under the hood laying the groundwork for a bunch more AI-based processing in upcoming point-upgrades.

Logic Pro 10.8.1: Logic Pro X 10.4.8: Details and buttons differ, but colouring looks the same to me.

I'm a little surprised you're not part of the beta program and running v. 11.2 pre-beta by now.

You'll be in the middle of mixing the next band by then...

Hang on... Compatibilty Open projects from Logic 5 or later — has this always been the case? I remember having to open Logic 7 to save some songs in a newer format — was that just for Logic 4.8 stuff?

Tech support nightmare. If everything goes well, breathe deeply, never let on, and file under "Let's Not Do That Again".

Err. Thank you. Fixed.

For further testing: Duplicate the project and remove all instances of EastWest. Does it work properly? Then EastWest is probably the (or at least an) issue. Duplicate the project and remove all instances of Kontakt instruments EXCEPT EastWest. Does it work properly? Then EastWest is probably not the issue.

Open up the system Utility "Activity Viewer" and from the Window menu, select "CPU History". Then play the project again. You will see how individual cores of your CPU fare, and you can see if a particular core is actually overloading. In the Logic Settings, under "Audio", set "Processing threads" to "Automatic" if it isn't, and if it is, try "8 (8 Performance Cores)", or if your M2 Pro only has six performance cores, "6 (6 Performance Cores)". The reason I suggest this is to make sure Logic isn't using the low-power efficiency cores to try and play sounds that may overload them. I doubt that will fix the issue, but.. My hunch is that you will have to pony up and pay for the EastWest upgrade to get it working properly. That's how the software industry finances development — by making you (eventually) pay for upgrades that you need for compatibility with newer machines/systems.

IMHO, it really sounds like a compatibilty issue. Especially given EastWest's, er…spotty support history, my money is on that particular plugin.

It’s called „vintage“ for a reason. 😜

Make sure all your plugins are updated to their latest versions. This may require paid upgrades if your stuff is from 2013. EastWest has made no official statement on compatibility with macOS Sonoma yet, so these are a little iffy IMO. Kontakt needs at least version 7.9. Omnisphere 2 is officially supported on Sonoma, but needs to be a fairly recent version. Also, make sure that your audio interface driver (if required) is compatible.

No option for multiple versions. I use 10.4.8 for one of my main clients, and 10.8.1 for everything else.

Are all of your plugins up-to-date?

I reiterate my advice from countless earlier threads: Keep a list of your OWN software — all third-party tools, plugins, device drivers, productivity software, etc. I have a table of ALL my stuff, with new columns each major macOS release: one for for links to support pages and one with checkboxes for certified compatibility and offical support. I don't upgrade until most of the vital software has official support for the new OS, but in situations where I don't have the option (such as when buying new hardware), I have a good overview of what might be potential problems. When I've upgraded MacOS despite some software not being officially supported, those pieces without checkboxes are always the first place I start troubleshooting when I run into any problems.