Open/close sidebar not working on iPad

Hi Running the Mendeley app on an iPad2, iOS 7.1.2 (really don't want to go iOS8.1 as it sounds way to slow on ipad2). I've noticed (only recently, not sure when though) that the button to open and close the sidebar in document view does not work. the icon changes (arrow left/right) but the sidebar remains open or closed. Often if i change orientation it starts to work, and then works for a while 9even when I orient back) but then stops working. More of an iconvenience than a major big, but still thought I'd report. Thanks! Jim