Logstash document_id for elasticsearch not incrementing

(Running on windows, latest versions of elasticsearch and logstash)
I've seen a lot of posts with issues (and fixes) about the document_id with elasticsearch, but none seem to be exactly my problem.... Below is my entire .conf

input {
    jdbc {
        # jdbc connection string to our database
        jdbc_connection_string => "jdbc:sqlserver://****"
        # The user we wish to execute our statement as
        jdbc_user => "****"

	jdbc_password => "****"
        # The path to our downloaded jdbc driver
        jdbc_driver_library => "C:\Program Files\Microsoft JDBC Driver 6.0 for SQL Server\sqljdbc_6.0\enu\sqljdbc41.jar"
        # The name of the driver class for sql
        jdbc_driver_class => "com.microsoft.sqlserver.jdbc.SQLServerDriver"
        # our query
        statement => "select EXID ,Name from myTable"
output {
	elasticsearch {
		index => "myIndex"
		document_type => "myType"
		document_id => "%{EXID}"

The thing is, when I do it like this, it DOES use the EXID as the document_id......but only the first one. So it grabs the first EXID and uses it as the document_id for all of them, so at the end, I still only have one document because they all replaced each other because they were all using the same id. If I take the document_id => "%{EXID}" line out and use the auto-generated ids, everything works fine. So it is just the delayed expansion that isn't working. What am I doing wrong?

That's weird. What if you remove some complexity by using a stdout { codec => rubydebug } output? Does the sequence of events look okay (specifically the EXID field)?

looks fine:
{ "exid" => 168, "name" => "Name0" } { "exid" => 169, "name" => "Name1" } { "exid" => 170, "name" => "Name2" } { "exid" => 171, "name" => "Name3" }

The issue was only with document_id, not the EXID. So when they were all being uploaded with the same document_id and replacing each other, the EXID field was incrementing as expected. So at the end, I had one document, containing of all the data, including the correct EXID, for the last entry, but with the first EXID for the document_id