If you stream your gameplay with OBS Studio, Streamlabs or OBS.Live (by StreamElements), use the 'Game Capture' mode, and w to display Overwolf overlay in your stream - please follow these steps:

  1. Open OBS Studio/Streamlabs/OBS.Live
  2. Open the settings window for the "Source" that captures the game client (right click on the source and select "Properties")
  3. At the bottom of the properties window, check the option "Capture third-party overlays"
  4. Save the changes

Overwolf should now be displayed correctly in your stream.