Missing Entry in LOG Viewer

I am trying to migrate from UTM to SF and want to go step by step.
Currently I try to work with the LOG Viewer, but I don't see the expected results in the LOG Viewer.

For the Sophos Firewall (FW) the interface to the Fritz!Box is 10.0.10.3. In the Fritz!Box I have created a new interface for 10.0.10.3 and send all traffic to port 8000 to the FW. 

There is no new firewall rule and no NAT rule created yet. Only the standard ones after setup. So I tried to access https://www.my_URL.de:8000/128.mp3.
My understanding is, that this access should logged, because there is no firewall rule and no NAT rule for port 8000 implemented yet.
For these tests I used my cellular phone (WLAN off) and also an external page.

At the specific time, where I tried the test, I can find anything in the LOG Viewer.

But I can see in the Log Viewer some denied https traffic (port 443).

So I don't understood, why I can not find any try for port 8000 in the LOG Viewer?
How is it possible to see some accesses to port 443 (https) in the LOG Viewer, these traffic should be only send to the UTM firewall?

Thanks for your support,
HGA