Reopening this now as it seems like X-Plane-12.0.8-beta-2 addresses the bug. Currently running X-Plane-12.0.8-rc-1 and it seems like all default aircraft now have correct windshield defrost/heat/anti-ice, however the CL650 and other payware aircraft (I've also tried the Airfoillabs King Air 350) do not have working windshield heat. Any idea why this might be the case?