I think I found a bug. Please share if you know more about it.
I use GetListItems operation to fetch items to display on an ajaxified form. Just an hour ago everything was fine, but now when I query the list with
<Eq><FieldRef Name='Some/Field'><Value Type='Lookup'>Value</Value></Eq>
The relevant items show up in the result set. But the values for 'Some/Field' (yes there is a slash in the displayname) are displayed as null. The field was never renamed.
What is it? How can I fix?