We do most of our development on OSX 10.12 and everything works beautifully there. However, we discovered that if we build the same codebase on an OSX 10.14 machine, then all Melda plugins, when their editor windows are opened, just display black. The same plugins (from the latest release from Melda) display fine on this 10.14 machine if I run a host built on a 10.12 machine
Below is an image using the JUCE plugin host from the very latest build from GitHub. I built this on 10.14 and as you can see, blank editor window.