M1 is giving me grief now, trying to open older projects which have M1 loaded, going back maybe 2yrs, Cubase 12 just disappears or hangs with a 'serious error' message.
I was also getting 'Invalid project' messages which is always a freakout.
To get around this Cubase has to be started in 'Ignore 3rd party plugins' mode, then when it opens, unload M1 which shows as 'missing' (as do all the other VSTis) in the plugin rack, then reload it and save.
The project will then open as expected but doing this is certainly clunky, to say the least.
This must be a 'backward compatibility' issue, since in an older project the version of M1 is older as well. Reload with the current version and voila, all's good but it took me a lot of figuring out which plugin was causing this.
Korg seems to be rather erratic in the quality, dependability department.
