Elasticsearch query not returning document source


I have an index 'company' with types 'branch', 'employee' (Names of index and types are changed from the real). Cluster has 5 primary shards, 1 replica. Type 'branch' has 276 records and in 'employee' type we have 5 records.

Refer mapping and query in the gist : https://gist.github.com/sarathrs/027a23da49a67c1ada2f

When i execute the query, source of the documents are not returned. Can someone explain why it is behaving so. Interestingly if i remove script_score from function_score query in should clause then query returns source.

Out of 276 records in type 'branch' query matches for 2 documents. must clause matches for 2 documents and should clause matches for 1 document