@lalalandsynth This happened to me when I was first installing on my Mac & XCode. I installed the newest version of JUCE & it worked but then I was no longer using the GPL licensed Projucer.
Once I completely removed JUCE & HISE source codes, I then redownloaded new_layout branch & built just fine. I do believe I had to manually select the Projucer within HISE Project Folder & change some settings in order for it to function properly.
Seems super simple & it sounds like you may have done this already but thought Id share my experience with this problem.