Tvheadend

Hello there.

Version of TVHeadend: 4.3-1979
    Running on Linux mint- 5.4.0-1132206031516-generic 
    No adapter/tuner chipset, since I am using IPTV only

I hope not to break some policy: under github there is a list of public TV streaming services (https://github.com/iptv-restream/iptv-channels) and I am using the list for Italy (my Country). Within that list, there is my preferred channel "La7" whose link is this:

#EXTINF:-1 tvg-id="La7.it" tvg-logo="https://upload.wikimedia.org/wikipedia/commons/thumb/0/02/LA7_-_Logo_2011.svg/512px-LA7_-_Logo_2011.svg.png" group-title="Undefined",La7
https://d15umi5iaezxgx.cloudfront.net/LA7/CLN/HLS-B/Live.m3u8

Now, if you use any program for viewing that link (under linux you can use Celluloid, for instance), you see correctly the live streaming.
I then set up Network/Muxes/Services under tvheadend; when I open the same channel (La7) I can see the channel, yes, but what it is shown is something back 4 hours and half in the past (!!!) and not the living event.

I can't understand how that is possible, because:
1) live event is live event and not something in the past
2) Celluloid shows the live event, tvheadend not !
3) the delay of 4.5 hours is clearly not an issee related to some time zone mislacement (there are none, tvheaded shows correctly the time and timezone)

This is driving me crazy !
Where am I wrong ?
Thanks