Glad to hear from you Noel!

I tried deleting all the lyrics and adding them again.
Things seem to go alright until bar 108, then things got strange.
The lyrics are just chromatic harmonica tabs, so they are fast to enter. I wasn't watching, then suddenly realized the lyrics were not going where they were supposed to go.

https://imgur.com/gallery/5WO4q


And what are the strange little diagonal lines under the top ledger line of the base clef?

It was a lot of work getting all the notes correct. 195 bars. I don't want to start over. I'll try saving it in a new file, but won't that just save the bug?

Is there some way I can rescue the melody and get it into a new file without the bug?

I pretty sure the problem began after inserting and deleting bars.