Elasticsearch Not Returning Document By Field Name - indexing

Question

Elasticsearch newb here. I seem to be having an issue selecting documents by a certain field. It feels like a corrupt index to me, but I'm not sure.
Here is a document that I can retrieve, and get the fields event.type and event.accountId:
$ curl -XGET 'http://127.0.0.1:9200/events-2015.04.08/event/AUyYpkl-r99VdGrSLpIX?pretty=1&fields=event.type,event.accountId'
{
"_index" : "events-2015.04.08",
"_type" : "event",
"_id" : "AUyYpkl-r99VdGrSLpIX",
"_version" : 1,
"found" : true,
"fields" : {
"event.type" : [ "USER_LOGIN" ],
"event.accountId" : [ 10399 ]
}
}
Notice the event.type: USER_LOGIN. Now I want to find all documents that have this field/value combination:
curl -XGET 'http://127.0.0.1:9200/events-2015.04.08/_search?q=event.type:USER_LOGIN&pretty=1'
{
"took" : 2,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 0,
"max_score" : null,
"hits" : [ ]
}
}
No results. I can find the document by event.accountId though:
$ curl -XGET 'http://127.0.0.1:9200/events-2015.04.08/_search?q=event.accountId:10399&pretty=1'
{
"took" : 2,
"timed_out" : false,
"_shards" : {
"total" : 5,
"successful" : 5,
"failed" : 0
},
"hits" : {
"total" : 2,
"max_score" : 1.0,
"hits" : [ {
"_index" : "events-2015.04.08",
"_type" : "event",
"_id" : "AUyYpkjCr99VdGrSLpIW",
"_score" : 1.0,
"_source": {...}
}, {
"_index" : "events-2015.04.08",
"_type" : "event",
"_id" : "AUyYpkl-r99VdGrSLpIX", # <-- This is the doc I want
"_score" : 1.0,
"_source": {...}
} ]
}
}
So is this field corrupt or something? How do I check? I expect to be able to find this document by event.type.
UPDATE
The document is being indexed with the SQS plugin to Logstash. Here is the relevant part of logstash.conf:
input {
sqs {
queue => "the_queue"
region => "us-west-2"
type => "event"
}
}
filter {
json {
source => "Message"
target => "event"
remove_field => [ "Message" ]
}
mutate {
rename => { "Type" => "EventType" }
}
date {
match => [ "Timestamp", "ISO8601" ]
}
}