No, it is definitely not normal for no sound to come out the Sub.

Does the Sub does show in the same room as the Beam in the app?

I would try rebooting the Sub to see if that makes a difference.

Unplug the Sub from power, wait 30secs, then connect power and see if you can hear it then.

I would just ensure too @Cindyschnoeb, when listening to the TV, that you are not playing a PCM 2.0 or Dolby 2.0 audio source, as that won’t give you any output from the Sub. Maybe play a movie or show instead that has Dolby Digital 5.1 audio and see if that gives you audio from the Sub.

The Sonos ‘Now Playing’ screen in the App will show you what TV audio input is being sent to your Beam/Amp Home Theatre setup, so check that for the type of audio source playing.

After removing the Sonos Sub from the TV room there is no change. We unplugged the Sonos Sub for 30 seconds and did a reinstall, the Sonos sub made a sound. However when I added it to my TV room, an exclamation point appeared with the mark "Finish" below.

We watch videos in Dolby digital 5.1

Is the Beam wired to your router and have you possibly disabled Wi-Fi on the Beam?

The Sub should connect to the Beam over the Beam’s 5GHz radio so needs WiFi to be enabled on the Beam.

I would also reboot your router to see if that then establishes the connection of the Sub with the Beam.

The beam is connected by ethernet and the sub by wifi. Will the problem come from there?My WiFi-connected equipment is 2.4 GHz

The beam is connected by ethernet and the sub by wifi. Will the problem come from there?My WiFi-connected equipment is 2.4 GHz

Make sure WiFi is turned to ‘On’ for the Beam.  Regardless of the Ethernet connection, it still needs to be On for the private 5 GHz connection to the Sub.