Your thermostat is not linked to a module located in its main zone, but to a module located in one of your secondary zones.
In the secondary zone, the regulation is done by the radiator, hence your thermostat does not know when you are heating. That is why you do not have the heating times visible in the statistics.
To solve your problem, proceed with pairing the thermostat with one of the heating modules located in the main zone of your thermostat:
In order to associate the thermostat with the module, it is necessary to put your heating module in 'pairing' mode.
To do this, tap quickly several times in the centre of your heating module's case until you see the three LEDs scrolling. Then, wake up the thermostat by placing it over the heating module in order to make the association.