Cannot delete records for games without a game termination marker.

[RogerMarsh]

Such records arise from spurious text between a valid game termination marker, '*', '1-0', '0-1', or '1/2-/1/2', and the first PGN tag pair of the next game; or from other, often matching, values in the 'Result' PGN tag and the game termination marker position in otherwise valid PGN movetext.