We have confirmed this is a real bug, and it is affecting Steam installs only. The install is missing files. For a temporary fix, you can install the replacements manually. We will put out an official fix on Steam as soon as possible.
Download the missing files here.
Unzip the files.
Go to the X-Plane root folder:
- Right click on X-Plane
- Choose Properties.
- In the rising window choose LOCAL FILES.
- And than choose BROWSE LOCAL FILES.
From there, go to Resources > default scenery > default ATC > Voices and replace the existing, empty "default" folder with the entire unzipped folder.