Use text/Value in Azure Monitor Query Variables

According the Grafana docu (see ) it should be possible to use special column names __text and __value within queries. In the resulting dropdown for that variable, the __text is shown, but the variable gets the __value content.
Tried this with Azure Monitor : Does not work.
This is the last line of my kusto statement i used:
| project __text=runDate, __value=BuildID