starting with Sphinx 2.1.2 the used sql_attr_str2ordinal in:
are now deprecated according to:
and probably will be removed in future versions of Sphinx. According to the shown message:
WARNING: key 'sql_attr_str2ordinal' is deprecated in /etc/sphinxsearch/sphinx.conf line 39; use 'sql_attr_string for sorting' instead.
it should be replaced by: