You need to make sure all the sensors you put in the group have the correct name. I would check your sensors names and states by going to this page and look them up. Make sure you copy the name exactly into the group as if you get the name wrong its not an error, it just doesn’t show up. You can share your group configuration so we can see if it formatted correctly if the names appear correct.
One of my groups, correctly formatted, note the spacing.
Sorry,I think I didn’t explain my issue very well
In my group I have the two sensors I set (temp and humidity).
Now I would put under each sensor, the line with latest update, like in the image in my 1st post (the gray line with ‘9 minutes ago’ for example)
I think this comes from a very old version of Home-Assistant (0.2X.X or somthing like that), but I may be wrong. However, if that is the case you should be able to see when was the last update using templating and relative time (but it is a more advanced feature, not really straightforward for a newbie).