RFID Tags: I don't receive any "tag_scanned" event

I am a Newbie to HA.
System: Supervised, Core 2024.3.1, running nicely as a VM on an Intel QNAP.

Have great successes with ESPHome, a micro sized ESP32mini C with an attached underpowered ZKTeco Keypad/RFID-Reader without any level shifters. Works like a charm. Part of my code is:

  - id: mykeypad
    d0: GPIO0
    d1: GPIO1
      - lambda: ESP_LOGI("TAG", "received tag %s", x.c_str());
      - homeassistant.tag_scanned: !lambda 'return to_string(x);'
      - homeassistant.tag_scanned: "1647562759"

I see tags scanned 100% reliably in the ESP log home screen (lambda: ESP_LOGI). I need to add that the ESP32 and Home Assistant are in different subnets, but with no firewall in between and Home Assistant/ESPHome and the ESP32 communicate perfectly, including OTA wireless updates/installs. So I can’t see why the communication should be in any way impacted (though mDNS won’t work).

Now I have the code above running and change over to DEVELOPER TOOLS/EVENTS and then listen to “tag_scanned”. Nothing! Absolutely nothing.

How can this be? Since I could not find in-depth documentation for the whole NFC tag business in HA, I thought maybe the event is only fired if the tag exists in the SETTINGS/TAGS list. So I fired an additional event in the ESP script for this tag only (see above), as a test, to assure the tag format is right and the tag exists in the list. Still nothing.

Can you guys think of any reason why the ESP32 with the script above is unable to fire the tag_scanned event or Home Assistant being unable to receive it? Is it possible that mDNS is required for transporting events?

On top, can someone enlighten me what the actual sense of the SETTINGS/TAGS list is? Is there any stage in HA that is performing a search/comparison in this tag list with actual read tags? If not, why is this list even there??? I found Tags - Home Assistant to be of little help explaining the basic communication concepts and flows for tags in HA.

Thanks for any help!

No one?
Can at least someone confirm to me that with an ESP32 sending the homeassistant.tag_scanned: command and with UDP/TCP traffic running fine I MUST see the tag_scanned event in the Event Viewer of Home Assistant?