Ant not respecting diffTypes=data

From http://forum.liquibase.org/topic/generatechangelog-and-difftypes#49382000000930007

generateChangeLog does not work in version 3.0.4 with diffTypes=data.

I am using a DB2 database and generateChangeLog runs without error but the result is a xml-file with table creation changesets only, like:

<changeSet author="Administrator (generated)" id="1379681415265-1">
<createTable remarks="" tableName="test"/>
</changeSet>
<changeSet ...

My parameters in the generateChangeLog task in the build.xml look like this:

<generateChangeLogDatabase
driver="${reference.driver}"
diffTypes="data"

url="${url}"
username="${username}"
password="${password}"

defaultSchemaName="${schemaName}"
outputFile="${dataFile}"

classpathref="lib.path">
</generateChangeLogDatabase>

It seems to work just fine for all other difftypes, except "data".

I tried the new 3.0.5 release and it reacts the same, except that it added a view changeset.
But there is definitely no data.