I have inspected the file.
The file is a .docx file and uses MS Word "not part of the OOXML Standard" text boxes. AOO does not support Textboxes (LO does) so textboxes and items within them do not display in AOO.
The file opens with OpenOffice and displays 23 pages where the page 23 is as below. There is substantial content below Page 23 in the XML file. "triangle" is at line 6,745 in NotePad ++ (pretty printed).
There are numerous <mc:AlternateContent> tags which are Microsoft's way of saying "The following content is not part of the OOXML standard". AOO does not understand anything between <mc:AlternateContent> tags. There are several occurrences before line 6,745 (the first occurs at line 4,129) so some content is not being displayed by AOO in the 23 pages I can see.
When I check the XML syntax NotePad++ gives the following error which I do not understand. The error "seems to be about where I would expect it" which is after the last thing I can see.

- error.gif (7.52 KiB) Viewed 1607 times
I think therefore there are two options.
1. I remove all the XML tags from document.XML. This will leave just the text content - at least the text will be saved.
2. I have posted the code causing the problem below to see if anyone can identify the error in the XML. The tags look a valid pair. If that error can be fixed then the .docx file should open properly, with all content visible, in LO. Unfortunately I cannot find a similar set of tags to use as a template to make a correction. I am fairly certain that the " pic " is incorrect in both tags but I do not know what to replace it with.