Trouble with the WHERE field in Dashboard Query

Defo a noob here but with a decent IT background. Any help gratefully received !

Having real trouble with my first Grafana Dashboard. Just can’t get it working at all !

My setup is within Home Assistant so I’m using the InfluxDB and Grafana (v 10.0.2) Add-ons within HA.

Config and setup of both Add-ons seems to have completed successfully and I can see data within Influx and to a lesser extent in Grafana.

My issue occurs when setting up my first Grafana Dashboard Query:
Using InfluxDB as my data source…
FROM field set to Autogen
SELECT MEASUREMENT set to (say) °C
(All good at this point with data displayed in the main dashboard panel)
But…
As soon as I choose anything from the WHERE drop-down I get a “No data” message in the main panel.
All the tutorials I can find want me to enter “entity_id” in this field, which I don’t have in my drop-down. The nearest I can see is “entity_id::tag” which produces the “No data” message. In fact it doesn’t seem to matter what I pick or freehand enter in this WHERE field I always get “No data”

Is this my rank stupidity or an I missing something ?