Liberating city states

Is it me or has liberating city states changed? I've played a few games on the easier levels to get acquainted with the changes and it seems to me that when I conquer an ex-city state then I can't liberate it.

It might only be cities that are Venetian puppet.

Anyone else notice this?

/Møller

Venetian 'acquisitions', as with Austrian 'intermarriages', cannot be liberated.