Hey ,
I wanted to touch base again with another suggestion to try and get your sound to work. Go into the ‘Config’ folder within the Unreal Projects directory for the project you are experiencing issues. Before making any changes to the .ini folders, create a copy and move them to a different location, like your desktop.
Now delete your projects .ini folders and save the changes made. Re-open your project and check to see if sounds work at all within the engine. Let me know if you have attempted this suggestions, and if it worked for you.
Cheers,