My guess is this will all turn out to be tragic, but highly ordinary.
The problem seems to be too many agencies involved, and too many reporters chasing rumors.
The sea is a big place, it swallows stuff up. We used to have routine Man Overboard drills in the Navy, where we threw a dummy over the side and attempted to recover it. Very often, even under flat seas and ideal conditions, we would often lose it. We were often cautioned in our training that there was no guarantee we would be found, even if we went overboard under perfect visibility and flat sea state. And there are currents. Things move around and disperse quickly.
We once had a submarine surface a thousand yards away from us and a half-dozen lookouts failed to spot it.