Cannot expand preview pane – Briefcase Pro - File manager, cloud drive, document & pdf reader and file sharing App Review

Overall this app works well, however I cannot expand docX files from preview pane to full screen. Is this a bug that needs to be fixed? Ever since I upgraded my iPad mini to iOS 10 I have had this problem. I have contacted app support twice and have gotten no response. Can someone tell me what the problem is here?
Review by Mars0513 on Briefcase Pro - File manager, cloud drive, document & pdf reader and file sharing App.