OK I think this is now fixed on develop.
Just to follow up here. I had the same crashes in juce_osx_MessageQueue.h when I tried to load the plugin in an iOS host (JUCE plugin host, Cubasis, GarageBand). I didnāt use Projucerās channel configuration, but I saw that I defined an inactive stereo input in my AudioProcessor. After I got rid of this, it worked as expected.