If I open a book with the tablet in landscape mode, the pictures are large. If I then flip to portrait mode, the pictures stay large and are cut off on the right side.
If I open a book with the tablet in portrait mode, the pictures are small. If I then flip to landscape mode, the pictures stay small even though there’s room on the screen to display them larger.
Toggling Day/Night mode resets the picture size to be correct for the current orientation. And then it stays stuck at this new fixed size when changing orientation again.
From the forums: