Weird, I had suspected maybe I played off an old save file from before the trophy patch so I started again with a recent save file and still nothing.

After that I deleted all my old saves and started a new save (but still didn't erase my medals) and just did Ambushed trying to get Brutal Expert. I killed the five guys and it gave me the medal (even though I already have it) and the trophy.

if you save over an old save file which has locked trophies it will lock trophies for the new save.

My advice is to go just start a new game rush through / get those few trophies along the way

i had the same problem when i quit playing it for a while then came back to it and i got the medals but no trophies but sadly i had to clear saved data and start from scratch to get the trophies to activate again

Hmmm i never had that problem i know u can pick up a shotgun and get as many kills with it and die and respawn from the last checkpoint and it will carry over the kills from before u died

Did you download the patch, or download the patch in the after starting the game???

Have you tried deleting the patch and then reinstalling it?