No more sound in my UE C++ project : in project settings mix icons are grey , why?

I work on my UE C++ project since few weeks and suddenly I can not heard sound ( voice , music , sound , …) when I click on the sound in the content browser . If I create a new UE project the sound is working.
Have a look on the project settings picture attached : on the left picture my project without sound and on the right the new project with sound working.
Why on the left the “mix” icon are grey ? Is it the root cause of my issue : no more sound ? How to fix it ?
Nota : if i compile the project and I launch the exe file : the sound is working.

I have solved the issue , I have deleted in the project the directory binaries,Intermediate, build, saved and now it works … Don’t ask me why … :upside_down_face: