How to select values from two different Influx queries for transformation "Add field from calculation"

Dear community

I am trying to substract/add two influx query results via a transformation “Add field from calculation, mode: binary operation” in order to present the difference as a bar chart alongside the original query results. Each queries returns a timeseries of a specific forcast run (solar production forcast for PV plants) and I want to display both runs and the difference between them.

I have achieved exactly what I wanted in a test pannel which only contains the two queries and the transformation. In that case, Grafana automatically detects the two queryresults as “Value1” and “Value2”.

However, in the productive pannel where I want this to be integrated, there a multiple other queries from different sources (postgresSQL and CSV) . In the transformation options dropdown “field or number”, there is only “Value” option to choose from. The influx queries themselves produce correct results and are displayed without a problems.

I have been able to reproduce the error in the test pannel by adding a query to the CSV-Datasource. When the Datasource is added the two Query results Value1 and Value2 get lumped together as “Value”.

I seems to be a Bug (or a feature) of the CSV Plugin. However if I was able to give the results of the influx Queries an alias that was recognized by Grafana I suspect the transformation would work. I have tried overrides but that doesn’t help for the transformation.

How can I get Grafana to diffferentiate between the two query results. Thank you in advance for your advice. (using Grafana v8.2.5)

P.D: This is my first post in this forum so I apologize if the problem is a bit off topic or should be posted as a bug of the plugin, or as a matter of giving influx query results aliases…