If you're trying to share an application window on Mac while presenting and you are not able to find the particular application you wish to share, here's what you need to do to fix it.
- Ensure that your app window (e.g. Powerpoint) is not in full-screen mode when sharing the screen.
Ensure the app window (e.g. Powerpoint) is visible in the background and not minimized to tray.
If not, the PowerPoint will not appear in the list of applications due to full-screen mode limitations on Mac.