There is a lot to like abou the iOS 10 update. The new maps layout is better and one can finally set the routing to avoid tolls. But, I opened the book I was reading in iBooks on my iPad and instead of the normal two-column layout in landscape orientation I get one giant column.
I don’t recall there being a setting for this but I go looking for one to no avail. The iOS 10 iBooks app seems to have taken a giant step backwards. Reading a single column in landscape mode is, well, awful and an iPad pro is too large for me to comfortably read in portrait orientation.
Fortunately, I won’t buy books with DRM that locks me in to a single provider so I was able to move my ePub over to MapleRead which is a decent ebook reader. It has a lot of great features that iBooks lacks though it sometimes gets the formatting not quite right. But, in this case it continued to properly do two-column layout in iOS 10 so the problem is an iBooks-specific bug (don’t even try to tell me there is a good reason for it).
So, if like me, you are having issues with iBooks and you have the option to use any non-DRM ebook reader then check out MapleRead. I have the SE edition since I keep my books in Calibre and MapleRead can talk to Calibre directly.