I strongly believe that iron ore liquefaction ultimately proved the ship's demise. More about how this can happen here[1]. The facts all line up:
- Tons of water likely getting into the cargo hold, wetting it down, especially if the
crew didn't take care of shutting the cargo hold top.
- Lots of rocking back and forth
- They were carrying tons of iron ore
- That stuff can absorb a ton of water, then when rocked, let it all loose at once,
thus causing a top-heavy rocking motion that will capsize a vessel within minutes.