[4.8.3] Why does GetUnfocusedVolumeMultiplier() not work?

I tried to call FApp::GetUnfocusedVolumeMultiplier(); after setting the UnfocusedVolumeMultiplier config so it would update without needing to restart the game. But it did not work.

The code Im using first sets the config via:
GConfig->SetFloat(TEXT(“Audio”), TEXT(“UnfocusedVolumeMultiplier”), TempMulti, GEngineIni);

Then calls FApp::GetUnfocusedVolumeMultiplier(); which is the only publicly accessible means for 4.8.3 to set the UnfocusedVolumeMultiplier variable in FApp. (That I know of)

I know that the config is changing properly because if I exit the game and restart, the configs are properly updated and it works once restarted.(Meaning: it plays while unfocused based on the config)

But the call to FApp::GetUnfocusedVolumeMultiplier(); doesn’t seem to do anything.
Is there a way to immediately update the UnfocusedVolumeMultiplier in 4.8.3?