Irregular updates Sensors

Lately it seems my sensors getting updates irregularly (or it seems that way). I am using a temperature sensor that is broadcasting every 2 minutes to a MQTT broker and that works quite well. My HASS instance is set up with a temperature sensor that picks the value from the same MQTT topic. This has been working very well for over a year.

However I noticed something strange. From below screenshot you can see on 9:39:55 a reading was received but the popup says last updated “51 minutes ago”. Also it says “unknown C” (Celsius)

Here you can see the messages from the MQTT broker:

The readings are coming in every two minutes, so I am bit confused why HASS is showing some strange irregular information. Has anyone else experienced this also? (I am using version 0.37).

Cheers! Sacha