Note an interesting six-hour return to the area west of the Bevington Object, from approximately 2000Z on 14 Aug until 0200Z on 15 Aug. The expedition initially searched west of the Bevington Object on the 13th; the eastern portion in the morning, and the deeper, western portion in the evening. A day later, on the evening of the 14th, they returned to the area and searched a very specific track from east to west over the period of six hours. After this six hour search they transited out of the area, went into what appears to be a holding pattern for the better part of a day. Since then they've circled the island, and today "mowed the lawn" on the deeper reef slope, southwest of the Bevington Object, west of the Norwich City.
Just hazarding a guess, but it could be that they have located something of interest west of the Bevington Object, but have determined it prudent to get the search completed before moving into a recovery phase.
A screen print of just the six hour search track, 14 Aug 2000Z - 15 Aug 0200Z is attached. I omitted Nautilus' track before and after; including the "mow the lawn" searches that occurred on the 13th. The track segment in grey is a period where there was no geo position reporting for greater than an hour.
BTW, I'm using the "Big Ocean Data" free trial period. Very interesting tool once you get the hang of the user interface. Amazing that the average person can get their hands on shipping tracks, air tracks, etc. these days(!)