Volume Adjust Sounds in Boot Camp Are Gone

Hello!

After updating to MacOS Sierra 10.12.5, the start Sound of my macbook as well as the volume adjust sounds have disapeared.
Today, I updated to MacOS Sierra 10.12.6. The start Sound is here, but the Volume sounds in Windows dont work.
Also another friend reported me, his Screen doesn't become as dark as it was before and is still possible in MacOS.

I would ike to get back the Bootcamp sounds and also if you have similar issues and an idea how to solve, please help.

With best Regards,
Firebird