Is the driver's head not moving even with NeckFX on? Follow this guide!
Method 1
Open Content Manager and go to Settings > Custom Shaders Patch > NeckFX
Untick the active box
Method 2
Go to Settings > Custom Shaders Patch > NeckFX
Untick Active for “Replace Original CSP implementation with a custom script”
Method 3
If your neck fx still is not working, make sure your render mode in Content Manager > Settings > Assetto Corsa > Video > Rendering Mode > Set to Single Screen