Just noticed that the next/previous arrows when viewing an image inconsistently works/doesn't work.

The arrows are the ones just to the left of the "gear-shaped" icon on the right side of the red bar along the top.  They are highlighted for all the images on that appear on the first page of my gallery, but on all the images past the first page (when you scroll to the bottom or hit the "more" button at the bottom) have the arrows dimmed and are nonfunctional.  Is this by design?