All of sudden, @Voice can jump from the TOC to the selected chapters, but not to subtopics

I am using @Voice for a few months now on daily basis. But all of sudden, it stopped jumping to the selected chapter.
 
The problem is peculiar, as follows:
I use the top-left button, which looks like a combination of three horizontal lines with a megaphone, which pops up the Table of Contents. This particular book has main chapters and subtopics in each chapter.

• If I select any main chapter in the TOC, it jumps to that chapter.
• If I select a subtopic of any chapter, it does not jump to that subtopic or even that chapter.
  Instead, it starts from the beginning of the book. 

I uninstalled @Voice and re-installed, but still the problem is there.
 
This problem started from today only. Earlier, it worked with the same book correctly.
 

Unfortunately, the file cannot be shared.
 
By coincidence, the file was updated, and the updated version was available in my laptop.
So I connected the phone with my laptop, and did the following using my Windows file browser:
1. Deleted the old version from my phone, and
2. Copied the updated version of the file from my laptop
 
The updated file has a different file name.
So I expected @Voice to produce an error, because it does not find the file.
Instead, @Voice kept reading from the old file, which actually did not exist.
Does @Voice maintain its own copy in a separate memory area, or is that buffered content? 
 
****
Back to the main issue:
@Voice still cannot handle the new file either, but now it has a slightly different issue:
When I click on the TOC, the display shows the right chapter or subtopic. But the @Voice screen display starts a few sentences above the desired landing place, and starts reading at the top of the screen. Thus it reaches the landing spot after reading a few sentences.
 
The desired landing spot is either 80% down in the screen, or just below the bottom edge of the screen.
 
The Full screen and break text in pages controls change this behavior a little, but I could not find a pattern.

This is a pdf file, and I am not aware of any prior conversions. But there seems to be no problems with it: When I view this file on my laptop using Foxit pdf Reader, I am able to jump precisely to the chapters and subtopics. 
Further, I clicked on the TOC at the beginning of the file, and also the bookmarks in the left panel of the pdf reader.
In all four cases, I can jump accurately, and the landing line is always aligned to the top of the screen. 
 
 
Curiously, this is true even when the landing place is just above 2-3 lines of the bottom of the page. 
(When I create bookmarks in a pdf file using Foxit pdf reader, it cannot achieve this with such landing places: The view lands on the next page.)
 
BTW I tried to add the file with- and without pictures, because there is a possibility that the presence of images may mess with the function. But this has no effect.