[fausto]

I'm still having problems with this text file. Not every chord line will transpose. I've tried cutting and pasting all the text to and from Windows Notepad (to remove any unwanted formatting), then deleting and re-importing the file using the companion but still certain lines (with chord symbols only) will not transpose. 

What am I doing wrong? Could this be due to line length too?

Sorted! My son had sent me the original as a Word .docx which I had dumbed down to .txt. However, I only just spotted he used "FMaj7" as opposed to "Fmaj7".
So, what was happening was that any line with FMaj7 would not transpose. As soon as I changed it to lower case M, all was well.