Views filters date fields by language and I don't know why.

Hi,

I'm pretty new to Drupal and I'm working on a site as a side project. I pretty fluent in the UI by now, but haven't done any coding yet.
Anyways, I have a content type named "test" with a datetime field named "field_xxx". I also generated some node with devel.
Now I'm building a View, which should only show me nodes of the type "test" and this is the only filter I use. But when I add the field_xxx (datetime) to the fields list I get no results at all :/
So I looked at the SQL that views generates and see this
WHERE (( (node.type IN ('test')) AND (field_data_field_xxx.language = 'en') ))

I figured it's because I locale module enabled, cause when I disable it the language = 'en' disappears and the query gives me the desired results. It always filters by the default language. I will eventually need the locale module since I want the site in a different language.

I can't figure out where to set or change this filter, which views seems to add by itself. Or even where to change the language property for the date fields. I look at the database table for this field and language is set to "und" for all entries.

Can anyone help me with this? Is this a bug in a module or in my head?

Thanks in advance