PDF: Highlights in images correct, copied text from highlights truncated

[wonderose]

I generally have PDFs with two layers, one image, one text, reading them up to now with Foxit Mobile Reader on Android.

This is what I just found out: from time to time Foxit truncates the copied text. The highlights and the underlined passages on the image itself are as I want them to be. However, the text copied (from the text layer of the PDF) into the annotation box is very much shortened.

I'd like to ask two questions:

1) What could be the reason for this erratic behavior? A simple bug in the app? Problems with the structure of the PDF file? Or something entirely different?

2) Less theoretical is this question. I now have to redo the annotations. As I can see the correct ones in the image, I'd just have to highlight and underline the specific parts of the image a second time, and everything should be in order. However, it took me quite some time to come across this problem, and by now I do have a few dozen of files that are to be reviewed. I was hoping there was an automated procedure of recopying the text from the image (using any desktop software there is). Yet, I couldn't find anything. Has anyone any ideas on this?

Thanks a lot for any help!