Do contact sensors and motion detectors behave differently in entry delay

Here’s a scenario I’ve been testing that I’m confused by. In this scenario, I have two contact sensors (front and back door) and one motion detector. The front door sensor is a “main door” so it allows entry delay. The back door is not a main door so it would trip the alarm immediately if it were the first breach of the property. The motion sensor is in a room (not entryway) so it is also set to trip the alarm immediately. Here’s the experiment I did: I put the system in armed/away mode. Then I opened the front door to put the system in 60-second entry delay. Then, during the entry delay, I opened the back door. Result: the alarm sounded immediately and called the monitoring service. (I’m in practice mode, so no harm.) Then, I repeated the experiment (again, starting in armed/away mode), but this time I ran in front of the motion detector during the 60-second entry delay. Result: the alarm did not go off. (The event history shows the motion detector did see me.) Instead, it continued to give me the rest of the 60 seconds to disarm the system, which I did. Both of these devices trip the alarm immediately without delay if they are the first breach of the property, but they behave differently when the system is put in entry delay by opening the front door. Why is this? Are motion detectors and contact sensors just programmed to behave differently during the entry delay, regardless of how they are set up in your account?