Problem with reordering pages

I'm having problems reordering pages.  My project now has 20 pages.  Ten pages at a time are visible on the page manager.  When I scroll down to reorder a page numbered 11-20, when I begin to drag it in the page manager to reorder it, it jumps to the spot on the list of the items 1-10 and I'm not able to get it beyond page 11 by dragging to the bottom of the screen.  For instance, if I have pages 11-20 displayed on the page manager and click page 13 and drag it down,(i.e., to assign it a higher pager number) the page manager locates it immediately after page 2 on the scrollable page list in the page manager, and I can only drag it to after page 10.  In other words, as soon as I start dragging it, the page manager assigns it postion 3 on the list and not position 13.   I hope that description makes sense.  Is this a bug or am I doing something wrong?  Thanks.