I have response from IK Multimedia (I have open case with IK):
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HI, Thank you for you're email we will be happy to help you with this.
Maverick support is not official yet, so use it at your own risk for now.
We will have updates for any issues with the current line of products. Older plugins will not be updated.
There is an issue with Garageband as they updated a lot of code that effects certain plugins.
It will not work until we update amplitube and I dont have a time frame for this.
Jason Williams
Senior Technical Support - IK Multimedia
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If I understand (I'm not english) ...IK Multimedia don't have time prevision for resolve this problem.
Apple don't response on my case...result= I'm not able to play guitar 😢 ...