with El Capitan, i can no longer see syntax error messages while writing core image filters inside Quartz Composer. It used to display error messages while writing the kernel code now it displays nothing. I mean inside the "Core Image FIlter" patch. Anyone experiencing the same issue?
Quartz Composer - Core Image Filter syntax error messages are not displaying
I have faced with same problem. Maybe it's happened because there is no Graphics Tools for XCode 7.3.
It stopped working for me when i upgraded to El Capitan in August 2015. So the bug exists for a while. I think they changed something in their new compiler.