Gotcha - I hope... lol - Does this look a bit closer then?
and I am not aware of a name for that body of water there between the islands, other than South China Sea. Anyway, nothing obviously wrong with the group, so the usual possibilities apply in speed changes, sharp turn, running single file, escorts are extremely "wild" in their "guarding" the convoy, plus your attacking. Notice also that the tanker is the "Leader" unit, so if it is sunk, the "Leader" baton must be passed to another ship, which can create the AI all sorts of confusion. I am setting up right now though, to "observe" what I can in the area near August 13, 1944 (checking the ships also, prior to sailing)...