Sound bug outside session

I’m experiencing a bug in my UEFN session (only in this session, so it’s not a general UEFN bug).

When my session is running and I’m in any window on my computer that isn’t my UEFN session, the ambient sound from the Collectible Object is constantly playing. This happens whether I’m on my desktop, browsing the internet, or anywhere else. As soon as I click on my UEFN session and go into it, the sound disappears.

I think that just before this bug appeared, I touched the “Level Editor Volume” and clicked the small yellow button that says “Custom scalability settings may affect…”. Perhaps this is a clue to the bug?

In any case, it’s unbearable, and I really don’t understand it.