CSI in AP mode: how to get CSI from known devices which are not connected to the ESP32 AP?

[maxplank]

Even if no station is connected to the ESP32 when it is in AP mode, I see CSI is being extracted from WiFi packets coming from unknown/random MAC addresses.

However, I don’t see any CSI being extracted from the packets my smartphone is sending to the Home AP. Does my phone need to send certain types of packets to the home AP so that ESP32 AP can extract CSI from those packets?

N.B. Both ESP32 AP, Home AP, and phone are in same WiFi channel.