How can I determine the last time a query was executed from the redash database?

I’m trying to use the Redash db queries table to analyse the usage of tables within our data warehouse. In particular, to determine the last time the queries have been executed/refreshed.

I’ve been using this select query to join queries with query_results:

from queries q
         left join query_results qr on q.latest_query_data_id =
where not q.is_archived

In most cases the retrieved_at column gives me the same value as the refreshed at data in the widget.

image image

However, for some queries the retrieved_at column is disappointingly null, although the refreshed data is shown in the widget.

image image

So, a couple of question:
Am I interpreting the queries.retrieved_at column correctly?
For the second query, where is the refreshed at data being loaded from?

Thanks in advance,