sort_fields option

Further to a previous enquiry I have used the search_fields option to specify what is viewable in the drop-down menu. My shortcode was as follows.

[pdb_list template=”flexbox” sort=”true” search=”true” search_fields=”boat_model,build_year,boat_length,price” fields=”boat_photo,boat_model,boat_name,boat_length”]

I then thought that there might be a similar function for the sort fields and so I included sort_fields=”build_year,price” into the shortcode. Unfortunately it didn’t work. Is there such a similar routine which would allow me to specify what options are available in that drop-down menu using the sort option.

Thanks