Is The Pzb System Working As Intended?

Okay, I freely admit this could be me just not understanding something, but having read the manual for the Steam version, and watched and read several tutorials, the system just doesn't seem to behave the way it's described.

Once I release from the initial restricted monitoring, whenever the train passes an active magnet, it just sounds the alarm, and applies the emergency breaks stopping the train. I get no warning or chance to acknowledge, no 1000 or 500 hz lamp display, just a red "S". Speed doesn't seem to be a factor either, as it happens even when crawling past at 20 kmh.

Can anyone help explain, or confirm if there is a bug here?

Thanks.