The (Temp) value is not displayed in the BasicUI

In the Events.log I get an entry for the (temperature) change. But in the Paper UI there is never a value. If I create a second item with a different name, everything works as usual. The connection is made via “Parent groups”, directly in the “Paper UI”. I have restored the system via a backup. Could this be the reason? I would not like to change my name convention.
Does anyone have an idea?

(openhabian/ openhab V. 2.5.11-1)

When posting a question like this please show the the configuration of the item.

Try adding a %.1f to the item label. The number (1) being the number of decimal places:

Number    RPi2Helper_Temperatur  "CPU Temperatur [%.1f °C]"       

Could we see that too?

In the post title and post body, there seems to some confusion with PaperUI and BasicUI. To see it in Basic UI there is also a sitemap entry to consider.

Ok, then a little more detailed:
I create, to a channel of a zWave- Thing, an item (HeizungBuero_CurrentTemperature) via Paper UI and add it to a group. In the Basic UI I show all values of this group:
Group item=gAktTemp label=“Current Temperature [%.1f °C]”

If I name it according to my default, then the value change for the item is logged, but in the Basic UI there is nothing. Not even a “-”. As if the item was not initialized at all.
To illustrate, I created a second item and also linked it to the same channel. The settings are exactly the same. Here I get values displayed in the Basic UI. It seems that there is a problem with the name. I don’t understand which one?

and the log:
2021-01-07 00:13:45.678 [vent.ItemStateChangedEvent] - HeizungBuero_CurrentTemperature changed from 13.11 °C to 12.67 °C

2021-01-07 00:13:45.685 [vent.ItemStateChangedEvent] - HeizungBRo_CurrentTemperature changed from 13.11 °C to 12.67 °C

The value of the second item (HeizungBRo_CurrentTemperature) is displayed, the first item remains empty in the Basic UI. It seems like there is a problem with the name. I don’t understand which one?

The [%.1f °C] here applies only to the (possible) display of the Group’s own state.
In this case, this Group has no state to display, because you have not asked for one with an aggregation function like AVG.

Long story short, this has nothing to do with how your Item state is displayed.

If that’s the one that does not display, this is the Item we need to see your definition of.

Yes the group item works well:
Group:Number:AVG gAktTemp “Temperatur [%.1f °C]” (Setting) [“Temperature”]

But the details look like that:

And the Item is configured like that: