Since the update to version 1.2.3 there have been some weird issues when it comes to the 3D sound fading of the slat sounds in the cockpit. Before this version the slat sounds were clearly audible in the cockpit, with the Flap sounds being rather muffled (i.e realistic). As of update 1.2.3 and 1.2.4 the slat sounds are inaudible when positioning the camera in the captains or first officer seat. Yet when you move the camera near the glare shield the slat sounds suddenly pop in. 

Here is a video demonstrating this weird bug. (sorry for the low res due to file size restrictions) 

I'll pass this along to the team, thank you for the media 🙂