[palosanto]

I have a strange problem trying to replace a pdf which is the base file for a song collection:
I have a pdf with a bunch of songs. I created a csv and split the song collection based on the pages where each song occupies and the pdf was split in individual songs correctly.
I noticed after a few days that there were a couple of pages in the pdf that were kind of blurry so I re-scanned them, updated the pdf and replaced the old pdf directly into the corresponding folder in the MSP files.
But now, when I go to any of the songs created previously, the annotations are gone and when I go to 'edit song>files' all the pages are listed instead of only the ones occupied by the particular song.
Nothing is different other than having now a cleaner pdf, but the same file name, same songs, same number of pages, etc.
I tried also via 'swap file' and I also loose the page index and the annotations.
Luckily I did a back up before updating the pdf.
What am I doing wrong?