Calling mongodump through mongos results in zero records when it should return the records that are in the database (in this case about 44000).

Mongos is running on the same hosts as one primary node. Behavior is not consistent though, sometimes it works.

Command used:
/opt/mongodb/bin/mongodump -h 127.0.0.1 --port 27018 -d db_production -c collection_views -q '

'

Set up has 3 shards, 4 nodes per shard.

There is a TTL index on this collection:

{
		"v" : 1,
		"key" : {
			"created_at" : 1
		},
		"ns" : "db_production.collection_views",
		"name" : "created_at_1",
		"expireAfterSeconds" : 432000,
		"background" : true
}