No. The problem is caused by the combination of Juce and Logic. If you override processBlockBypassed and implement a fade, it will work in other AU hosts, but not in Logic. I described the issue here a few days ago:
Currently this happens even with the JUCE demo project. Logic does not handle AU bypass correctly (like AULab and probably other AU hosts), but Apple examples do work right with Logic and it even applies fades by itself, but with JUCE it goes somehow wrong probably due to something the AU wrapper is doing that causes problems for Logic. I tried figuring out what part of the AU wrapper code causes the issue, but so far no luck and I’d rather not spend days on this as it’s mostly a guessing game.