I had a situation before where I could link meta data / site columns with managed properties to use is as a refiner in my search center.
I created the search center subsite under the root site collection and the site columns directly in the root. Everything worked as expected and visible under crawled properties as
In my new situation I created site columns in a (sub) site collection and again try to use this as refiners.
The issue is that the columns are not visible under "crawled properties" and therefore impossible to use as refiner. How to make this work?