I was also having trouble installing final cut/logic. I ended up needing to delete a few AppStore cache folders, immediately resolved the issues. ~/Library/C

I was also having trouble installing final cut/logic. I ended up needing to delete a few AppStore cache folders, immediately resolved the issues. ~/Library/Caches/com.apple.appstore, delete contents /private/var/folders click through the various letters and delete any com.apple.appstore folder contents. reboot