What Steffen_Volgmann said worked perfectly, try this
open terminal
sudo -i
enter root password
/System/Library/PrivateFrameworks/Seeding.framework/Versions/A/Resources/seedutil
Unenroll from the Beta Program
/System/Library/PrivateFrameworks/Seeding.framework/Versions/A/Resources/seedutil unenroll
Enroll in the DeveloperSeed Beta
/System/Library/PrivateFrameworks/Seeding.framework/Versions/A/Resources/seedutil enroll DeveloperSeed
Jerpyj
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