Select some (all) audio. Stop playback.
- “Select some audio” - Effects are all grayed out–why? - Special Interest Groups / Audio Processing - Audacity Forum
- “I’m betting that you “Paused” playback, so please try clicking the Stop button” - Menu options greyed out [SOLVED] - Audacity 3 Help Forum / Windows - Audacity Forum
Use File/Export Audio, not Save Project. More info:
- Export Audio - Audacity Manual
- “How do I save my audio for use in other applications? Does saving a project (AUP3 file) do that?” - FAQ:Opening and Saving Files - Audacity Manual