iOS App (Not) following hyperlinks in side-loaded epubs

[GibbinR]

I've recently downloaded the Kobo app for iOS onto my iPad mini 2 running iOS 8.2 and am experiencing problems with it.
Having side-loaded (using iTunes) a non-DRMed epub that works perfectly well on my Aura HD, I find that the Kobo iOS app does not seem to be able to follow hyperlinks (or the links in ncx file for that matter)
To clarify, the app clearly finds the ncx file and displays the contents list visually, and if one selects a location that location is visually highlighted, but the display then returns to the original page, rather than jumping to the selected location.
The same applies to HTML hyperlinks in the text.
I'm just wondering if this is a well-known problem, and I should just give up on the Kobo app, and go back to iBooks, or whether I could be doing something foolish.

[GibbinR]

Further note, I've transferred another pair of much more simply formatted epubs to the Kobo app using iTunes. In them the hyperlinks work but there are other strange formatting eccentricities which I won't bother to go into.
I'm beginning to wonder if the problem is really that the app uses the kepub rendering engine for epubs rather than ADE (an app for which has recently appeared in the app store). I tried the kepub rendering engine on my Aura HD a year or so ago and concluded it didn't implement enough of the epub definition to be useful, and, though I don't remember the details, this somewhat reminds me of that.
For now I'm giving up, and going back to iTunes or Marvin. Sorry to waste the time of anyone who started to look into this.

[davidfor]

I am pretty sure the iOS Kobo app doesn't use any Adobe RMSDK code. After all, it is a dedicated ereader app for Kobo's books. And as Adobe isn't listed in the acknowledgements, it's pretty certain.

While I have read a little bit using the app, they have all been books I purchased from Kobo. But, I would be pretty stunned if epubs don't work. After all, a kepub looks like an epub with extra spans. They should pass any epub validation you can find. But, I have just tried a couple of epubs on my iPad. They are rendering correctly and the ToC navigation works properly.

The two that I tried that had a contents page worked, but had some problems. On one, the links for the chapters were all down the left side. If I wasn't careful where I tapped, it turned the page back. If I was careful, the footnote display was popped up and then let me go to the correct spot. The other book had the contents list centred in the page. Tapping seemed to be easier and the links took me the chapter correctly. Looking at the code, I would say the reasons for the popups is that some of the links are to an anchor in the chapter rather than to the file. The rest was probably my fat fingers. Increasing the font size meant I hit the links more often.

Now, I have a lot more knowledge about the kepub reader on the Kobo e-ink devices. If you are producing epubs that don't render well using the kepub reader, then you must be producing some very strange epubs. The kepub renderer uses ACCESS (which has been renamed) and is a popular alternative to using the RMSDK based reader. There are differences in how they render the books or exactly what styles they ignore, but the kepub reader does a good job of rendering epubs. And it has done so for a long time.

If you have books that don't work in either place, post them for others to look at. Or, pick a book we can all look at to try. Picking a book in the MobileRead library works well for this.

[GibbinR]

First of all, thank you for replying to my original posts, and also thank you for your excellent advice in another forum to upgrade my Aura HDs to Firmware 3.12.1. That has worked very well, and I'm very grateful.
On the question of the epubs that don't work properly, the first epub that I tried, the one that doesn't follow hyperlinks, is a copyrighted work which I can't legally distribute. It started life as an old-fashioned mobi file (as opposed to azw3), which got converted to epub. The epub has over 500 xhtml files in it, mainly scholarly notes on the main text, so plenty of use of anchor points. The xhtml (which I didn't write) seems needlessly complex to me. I wonder if the sheer size and complexity may produce some timing problem where the (putative) kepub renderer simply gets timed out by iOS before managing to complete a request that should generate the new location in the book.
Regarding the two simpler epubs that I tried (after some more thought), they are the versions which I contributed to the MR library of 'Persuasion' by Jane Austen, and 'The Golden Bowl' by Henry James. In those publications, the hyperlinks seem to work ok, but the title page and chapter headings don't get centered properly. (And these do work OK in two generations of Sony Reader, as epubs on my Aura HDs, two generations of Kindle after being 'kindlegened' to azw3, iBooks, and also Marvin. They also pass error free in epubcheck. I haven't tried them as kepubs on my Auras.)
However, on further consideration, I feel a bit embarrassed about maybe having raised this problem before I'd really thought it through myself. Personally my overall conclusion is that (sadly) the Kobo iOS app isn't (yet?) a better substitute for iBooks, so I don't intend to take it any further, and wouldn't want you to waste your time looking into this in more detail to help me. Thanks again for your thoughts