line 257 i suggest it should be changed from AND i.C_Region_ID=l.C_Region_ID to
AND (i.C_Region_ID=l.C_Region_ID OR (l.C_Region_ID IS NULL AND i.C_Region_ID IS NULL)) to en-corporate null values. Because it seems to return no match when Location C_Region_id and ImportBPartner C_Region_id are both are null as for my case.

The line is on
247. Existing Location ? Exact Match
248. sql = new StringBuffer ("UPDATE I_BPartner i "
249. + "SET C_BPartner_Location_ID=(SELECT C_BPartner_Location_ID"
250. + " FROM C_BPartner_Location bpl INNER JOIN C_Location l ON (bpl.C_Location_ID=l.C_Location_ID)"
251. + " WHERE i.C_BPartner_ID=bpl.C_BPartner_ID AND bpl.AD_Client_ID=i.AD_Client_ID"
252. + " AND (i.Address1=l.Address1 OR (i.Address1 IS NULL AND l.Address1 IS NULL))"
253. + " AND (i.Address2=l.Address2 OR (i.Address2 IS NULL AND l.Address2 IS NULL))"
254. + " AND (i.City=l.City OR (i.City IS NULL AND l.City IS NULL))"
255. + " AND (i.Postal=l.Postal OR (i.Postal IS NULL AND l.Postal IS NULL))"
256. + " AND (i.Postal_Add=l.Postal_Add OR (l.Postal_Add IS NULL AND l.Postal_Add IS NULL))"
257. + " AND i.C_Region_ID=l.C_Region_ID "
258. + " AND (i.C_Country_ID=l.C_Country_ID) group by bpl.c_bpartner_location_id) " +
259. " WHERE C_BPartner_ID IS NOT NULL AND C_BPartner_Location_ID IS NULL"
260. + " AND I_IsImported='N'").append(clientCheck);
261. no = DB.executeUpdateEx(sql.toString(), get_TrxName());
262. log.fine("Found Location=" + no);