With further review it appears that by 26 May the USS Haddock had been relieved from lifeguard duty and was returning to base at Midway.
https://www.fws.gov/refuge/Midway_At...of_Midway.html
Attached is one last visual aid regarding the submarine lifeguard stations as identified by Rolland. The 26 May co-ordinates used here are the best found by me. These War Diaries are much like after action reports where the quality and content is much dependent upon the individual author. These are not meant to be literature but some are definitely better written than others however conditions on the boat at the time are to be considered.
All four of these subs report difficulties not only with their radar but also with communications preventing reliable comms with the Dumbo cover aircraft. One would think that this late in the war these communication difficulties for submarines on lifeguard duty would have been solved but such was not the case.
The War Diary (log) of the USS Pipefish is most telling. They were able to save several downed airman and also had the grim task of recovering others. Time was of the essence, many of the recovered dead were estimated to have been in the water for about 7 or 8 hours.
Anyway, nothing new here, B-29, 42-65273, “Big! Aint It?” and its crew remain MIA and likely will remain so.