The Verge article on the fall mentioned that the center core was different then your typical Falcon 9 and that the Octograbber wasn't compatible with the grab points on the FH center core.Bummer! I thought the Octograbber would handle rough seas.
/edit. Why they didn't get on there and weld down the legs like they used to do is another question, but perhaps the seas were rough right after the landing and they couldn't even get on the ship to do that safely.