Delta/V Australia seating problems on Delta
 

So booked a ticket from JFK-MEL via LAX all through V Australia though the first segment from JFK-LAX is a code-share on Delta and for whatever reason delta.com will not assign seats for that and shows seat map unavaliable despite your reservation being in delta.com and delta operating the first segment.

Also, delta.com won't even let u do online check-in despite again the first segment on Delta and you have a delta booking ref. number

Flight DL711/VA6514 JFK-LAX

Ticket was booked under the VA code. Call VA and they tell u to call Delta as its a delta operated flight but call Delta and they tell u they have no clue and they couldn't even assign a seat despite seats being avaliable and to call VA

Any thoughts?

You most likely wont be able to do online check in due to it being an international flight (I've never had success with this myself), even though the first leg is domestic, so that is what it is.

As for picking a seat, but did you check to make sure there were seats available for choosing (and not those that are greyed out for Medallions or those that are already reserved?)? That maybe the problem. My hunch is that this is just another one of Delta's many IT problems, assuming there are still seats left to assign.