How to re-enable the Unity sound system to run in paralell with Wwise?

Question

After installing Wwise into our Unity project, the built-in system was disabled, but we need to have both working at the same time while we transition to Wwise.

I have set: m_DisableAudio: 0 in AudioManager.asset, but that did nothing.

What more do I need to do to re-enable the Unity system?

EDIT: Actually, it does work in the builds, but not while playing in the editor? How come?