I am guessing either OP opened a song with embedded chords, thinking it's a style, or loaded another style demo on top of custom chords. Can't use Undo in both cases.

That's why we need a strong Undo, as many actions in BIAB currently are destructive editing. Or if action involves irreversible process have a warning with a "do not display this again" check box. I would still prefer a strong undo to any workarounds or warnings. The way, I am sure it is expected by most users to work....