Xiaomi Smarthome binding not reporting offline items

Hi all,
I have installed a Xiaomi smarthome gateway with 6 temperature sensors.
Of these 6 sensors, 2 are offline (because too far from the gateway).
In the Xiaomi app I see them as offline, but in the Xiaomi binding they seem to be online as they report the last temperature that was read in the past.

This is of course misleading as I cannot have the guarantee that the reported temperature is correct.
In my opinion if the sensor cannot be reached or is offline its state should be NULL.

This is the item definition of one sensor that is currently OFFLINE:

// Xiaomi Temperature and Humidity Sensor
Number nX_HT3_Temp "Esterno temp [%.1f ^C]" <temperature>  (gXiaomi) { channel="mihome:sensor_ht:xxxxxxx:xxxxxxx:temperature", expire="90m,NULL" }
Number nX_HT3_Hum "Esterno hum [%d %%]" <humidity>  (gXiaomi) { channel="mihome:sensor_ht:xxxxxxx:xxxxxxx:humidity", expire="90m,NULL" }
Number nX_HT3_Batt "Esterno batteria [%d %%]" <battery>  (gXiaomi) { channel="mihome:sensor_ht:xxxxxxx:xxxxxxx:batteryLevel" }
Switch sX_HT3_LowBatt "Esterno low batt" <energy>  (gXiaomi) { channel="mihome:sensor_ht:xxxxxxx:xxxxxxx:lowBattery" }

This is the log:

2019-07-13 10:25:48.618 [vent.ItemStateChangedEvent] - nX_HT3_Hum changed from NULL to 73.87
2019-07-13 10:25:48.621 [vent.ItemStateChangedEvent] - nX_HT3_Temp changed from NULL to 26.59

In the app, the sensor xX_HT3 is offline.

Is there anyway to report the OFFLINE status of the sensor?