Just discovered this last night when trying to open a BIAB/Logic project I hadn't worked on for a while. I don't know what the specific problem is because Logic just goes away with a debug screen. So, if you use Logic and are considering upgrading to the Monterey public beta, maybe hold off. I have a spare Big Sur iMac to use, but if I didn't I'd be stuck just hoping Logic or MacOS fixes this soon.

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UPDATE: The problem was EastWest's "Spaces" and "Spaces 2" reverb plugins. Removing those from my system lets the documents open, so I can use another reverb.

With Apple, there is no expectation of anything being fixed in a Beta OS—we can hope but there's never a guarantee. We're probably 3 1/2 months away from the public release of Monterey. Hopefully, any Logic problems will be ironed out by then. We'll see…

On the plus side, so far I haven't had any issues with BIAB 2021 in Monterey - so far everything's working as I expect. That's not to say the final release of Monterey will work - if you'll all remember, the major issues we encountered with Big Sur didn't come up until the release version.