Had the same just a few days ago with mine, apoparently when the remote battery runs down the hazards wont work on unlock - stick a new battery in the fob and it 'should' work.....mine did!
cheers... jus nipped out & it works with the spare fob... tried it about 5 or six times then, worked everytime, and yea mines the 2 button affair and i was just about to search for the battery type to then fleaby some batteries, saved me a job mate cheers!
On my jap import 300TDi the hazard lights have never flashed when use central locking.
Never bothered me before, but can anyone tell me if they should work when locking by remote.?