Erm.. PF = FP = Forge Points? GM = GB = Great Building?
If yes, it can happen that you click too fast (or the server/ your internet connection is lagging at that exact moment), then only some of your spent FPs are counted (but the additional ones are paid back to your FP counter)
If you're absolutely sure they that they have vanished, open an ingame ticket (right click -> contact support) and tell them the details, especially at which time (roughly) it happened.