I have found an intermittent weird behavior: When I add Power Attack as a temporary bonus, then the weapon to which the Power Attack is added is then listed twice in the inventory list (both when I make a PDF and on the Character Sheet tab). This happens consistently (and may be what you intended!). I've only tested this with a greatsword +1.
Sometimes the price of the 2nd greatsword is listed as 0 (which isn't too bad...at least my PC's total wealth calculation isn't screwed up) and other times (intermittently...sigh) it shows up as 50 gp less (the cost of the base item...not including the masterwork and the magic?) See the attached example.
Windows 7, Pathfinder