Keyboard shortcut: reassigning "Space" locks its functionality
Default: Space Bar will play the score. When entering chords or lyrics, Space Bar will advance to the next note.
Change the keyboard shortcut for "Advance Cursor: Next Beat (Chord Symbols)" to Space Bar.
Now, Space Bar immediately plays the score, even when trying to enter lyrics or chords.
To fix: "Reset Preferences"
Seems like the underlying issue is that MuseScore thinks that two actions can't be assigned to the same key.