I did not say that the hovering drone doesn't maintain altitude.
Here's what I said ......
But the ocean is not dead flat and a hovering drone doesn't stay a fixed distance above the water.
Ocean swells rise and fall, coming closer and falling...
If you saw 10 ft in orange letters on your screen capture,then I guess your drone must have been 10 feet above the sea (for the fraction of a second when that screen shot shows).
It seems that you've not learned a thing from any of your lost...
If you really had lost connection, pressing the RTH button won't have any effect.
Unless you've changed the Loss of Signal action from the default setting (RTH), your drone will initiate RTH 3 seconds after losing signal.