I connected to a SharePoint list data source. Here is an image which shows the data along with the column names:

When I edited the values in the gallery I was able to use the correct column names as can be seen in the image below:

But when it came to entering the column names in a Search formula it appears as "field_n" along with other column names such as "Editor". This can be seen below:

Here is a list of some of the column names that appear:

Does anyone know why this is?. Thanks in advance.