From my time flying the Q400 I seem to remember the flaps were very temperamental. Usually a mishandling of the flap lever could lead to the flaps becoming 'stuck'. Seem to remember that there was a reset which would normally fix the problem. I suspect what happened here is that on the first approach the flap became stuck so the approach was discontinued so that the reset could be completed. It probably appeared to have worked so a second approach was commenced but the flaps became stuck again due to a fault, so once again it was discontinued and the aircraft prepared for a flapless landing. All pretty textbook and certainly nothing to get to worried about.