Update: Last night I connected a UE Boom 2 Bluetooth speaker to my laptop to test out the voice acting, just to make sure there was not an issue with my headphones. With the speaker as the output device, I could hear the voice acting in cut scenes. Afterward, I disconnected the Bluetooth speaker and went back to my headphones, and I could still hear the voice acting. I am glad it works, but I have no idea what caused the voice acting to go silent in the first place, or why switching to a Bluetooth speaker and back would cause it to work again. I am still willing to provide a System Report so that it might help others who encounter this issue.