UEngine::GetMainAudioDevice()->GetActiveSounds() returns an empty array

I’ve just updated the engine to the 4.16 version. I’ve seen some changes in how to call some methods.
I can’t call anymore the GetActiveSounds() method from the game thread, but I must call it from the audio thread. Ok, I moved that call to the audio thread. It works correctly, but the call to GetActiveSounds does not return anymore the active sounds. I’m sure there are a lot of sounds: ambient sounds and other wave sounds spawned here and there.

Does something has changed in this new version on how to retrieve active sounds?

The same happens if I use GetActiveAudioDevice rather than GetMainAudioDevice.
The version 4.15 of the engine does not have this problem.