I think illusion, has got it, it is most likely that due to now having a full set of picks you are now able to aply more tension onto the lock. Too much which will make it far more difficult to pick. Also, now using real picks they will be able to move pins under a higher tension rather than simply bending, maybe encoraging more tension to be aplied.
Are you raking or trying to single pin pick the lock? Other than that its the obvious, practice will improve picking, good luck with it.