I'm having similar problems: BiaB Mac 2025, I’m moving along successfully entering lyrics in the notation window. Often when editing either notes or lyrics to fit syllables to music, things go awry. It seems to happen from either the Edit Note dialogue; or the Lyric entry boxes; or the Edit Lyric List dialogue. Suddenly lyrics will be moved to very odd places; several measures from where I’m currently working.
One suggestion - that apparently hasn't worked - was to delete the problem lyrics if I had copied/pasted one set of measures into another. I tried that to no avail.

Thanks for any thoughts