[TYPO3-mvc] Extbase Storage objects do not respect sys_language_uid

[Christian Essl]

I have a case in which Extbase doesn't seem to respect the sys_language_uid of some Storage objects.
sys_language_uid 0 = german, sys_language_uid 1 = english

It just displays _all_ the objects indepdendent from their language. I tried to output the $_languageUid: All the objects that are displayed are set to '1', when the website is in english mode, even the ones that are correctly set to another language in the database. What could cause such a behaviour?

TYPO3 4.7.2, extbase 4.7.2