Header fails to recognize chapter progress - bug?

[Skydog]

Occasionally I experience a lack of chapter information (header) in some of the chapters, typically at the beginning of a book. For example, Contents, Prologue, Chapter 1, etc., continuing for several chapters, will display only those titles. There is no Contents 1/1, Prologue 1/5, or Chapter 1/7. (no % available either) Oddly, beginning with Chapter 5, the count appears normally for the remainder of the book.

What's even more strange is that this only occurs on my Sage (v4.29) and Libra2 (v4.30). My trusty Forma (v4.26) does not display this problem, all chapter header info displays correctly throughout the entire book. All are patched to display "1/2" as opposed to "1 of 2" with no capitalization of titles.

I read epubs and all are sideloaded. Any idea what is causing this and why it happens only on later firmware?

EDIT: Performed a (second) book check for any auto-correction. Solved the display problem but the question still remains: Why did the older firmware display correctly?

[davidfor]

There are a few reasons you don't see the chapter progress in the header. The simplest is that there is only one page. In that case, you just get the chapter title.

The chapter heading is based on the ToC. Different things happen when the ToC entries do not have a one-to-one relationship with the internal files. If there is more than one ToC entry per file, then the chapter heading should change as you go, but the progress isn't always perfect. If there is no ToC entry for a file, then the chapter heading doesn't change when you go to the next file, but the progress might. I'm not sure exactly what happens with this as I don't have any books on my device in that state.

The ToC is built from the database which is populated when the book is imported. If this gets out of sync, then interesting things can happen. If you replace the book with a restructured book via calibre, you can get this. Removing and resending the book would fix this. And, at least for kepubs, the database has some numbers that have an effect on the progress and how it is displayed. Some of this is calculated when the book is imported and some when the book is first opened. If there are problems when these steps are done, it can mean some strange results later.

That is what I can think of off the top of my head. There may be other reasons, but, I might not have seen them myself.

[Skydog]

Originally Posted by davidfor

There are a few reasons you don't see the chapter progress in the header. The simplest is that there is only one page. In that case, you just get the chapter title.

The chapter heading is based on the ToC. Different things happen when the ToC entries do not have a one-to-one relationship with the internal files. If there is more than one ToC entry per file, then the chapter heading should change as you go, but the progress isn't always perfect. If there is no ToC entry for a file, then the chapter heading doesn't change when you go to the next file, but the progress might. I'm not sure exactly what happens with this as I don't have any books on my device in that state.

The ToC is built from the database which is populated when the book is imported. If this gets out of sync, then interesting things can happen. If you replace the book with a restructured book via calibre, you can get this. Removing and resending the book would fix this. And, at least for kepubs, the database has some numbers that have an effect on the progress and how it is displayed. Some of this is calculated when the book is imported and some when the book is first opened. If there are problems when these steps are done, it can mean some strange results later.

That is what I can think of off the top of my head. There may be other reasons, but, I might not have seen them myself.

Thank you, davidfor, for your explanation which helps me better understand the occasional problem. In this particular case I had converted an Amazon-purchased book to epub after importing to Calibre. Still, I always do a little bit of editing and did check the ToC to ensure its entries were pointing to a valid link. Apparently I am not knowledgeable enough since the "check book/fix automatically" solved the problem(s). Next time, I'll keep a copy beforehand containing the errors. What added to my confusion was the fact that my Forma had no problem displaying the chapter progression correctly (prior to the auto fix). The only difference being an older version of firmware installed.

Thank you again for your assistance with my never-ending learning adventure.