I am using SharePoint Online. I created a site column "Model" which is of CHOICE type. Two crawled properties ows_Model and ows_q_CHCS_Model are created automatically by SharePoint. I used the default managed property RefinableString01 to map ows_Model.
At search centre, if I type the keyword model:GL, the search result contains the images tagged with GL, and the refinement also works.
If I type the keyword GL, the search result does not contain the images I expected to see.
From the article What makes a SharePoint column searchable, I found that the crawled property ows_Model is marked with Included in full-text index; However, the managed property RefinableString01 is marked Not searchable. It is the default value which cannot be changed. Is there any way to make this column free text searchable?