I’ve been able to test the same shaders with latest iOS MG version and it also exhibits the same behaviour. Not working with the full version (geometry disappears) but removing instructions make the shader work.
I’m wondering if the problem would also happen in OpenGL. If it’s a problem of mojoshader it should also fail in OpenGL and should be easier to test. However for some reason I’m unable to get a working project in OpenGL in my rig.