The trans update is not shown as outstanding for my car. Perhaps it already has it.
Reading further on this forum, I see that trans fluid leaks (I assume at the input shafts) are common, can wet the clutches, and would probably cause the symptoms I am seeing.
Given the sudden and dramatic onset of problems in what used to be a perfectly-working DCT I remain very concerned. I will accept no nonsense from Ford on this issue. It is major.