It is possible that the opposite pole to the magnet in the outer part of the flap is at the bottom centre of the housing and therefore not immediately visible. Unfortunately, there is no exploded view of the flap on the internet.

Good evening
The magnet you are referring to is located on the outside of the flap and serves as a weight when the cat comes in from outside so that the flap springs back over the latch. If there was no weight on it (it fell off with the old flap), the flap would stay open after the cat has come in and other cats that are not welcome could come in without any problems. Our flap also opens automatically during storms, but always outwards, because the wind creates excess pressure in the flat and the air then goes out through the flap because it is movable. But only if the night mode is switched off.