Hi Alexander,
I have very strange error.
I have simple list with DFFS and vLookup to document library.
VLookup is configured properly – I can see child items (when fill lookup id manually), but I am not able to add new child item from parent form/listview. When click to “add new (child) item” button, nothing happens and in IE console I can see error “Uncaught TypeError: Cannot read property ‘match’ of undefined” (see attachment).
I tried september 21 version (with new installer), and August 11 version but with the same behaviour.
On the other site collection vLookup with the analogical configuration works fine.
Michal