That's not a bug, it is a feature 😉. The new version has support for the nashville numbering system. That means that the numbers 1-7 are also recognized as chords. If this bothers you, you can add a character to the line that is not recognized as a chord causing the line to be rendered as a plain lyrics line.
1 2 3 4 in Nashville Numbering system would be the chords (assuming the song is in C): C D E F