Adding the numbers, since they settle part of this. One practical note: write down what you did and when, before you need it. Reconstructing a timeline from memory three months later is how people end up unable to answer the one question that would have resolved it.

Correct me if the detail matters more than I have assumed.

One thing that is still open after Dr.NephBHM_UK’s answer:

How long did you give it before you decided it was working?

raj_cambridge said:

One practical note: write down what you did and when, before you need it.

Filing a mild objection. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit. The counter-case has not been addressed. Somebody upthread described the situation that does not fit, and the thread moved on rather than engaging with it, which is the failure mode this board is supposed to avoid.

raj_cambridge said:

One practical note: write down what you did and when, before you need it.

That is right, and it stops being right at the edges. The general case is well behaved; the interesting cases in this thread are all at the boundary where the general case breaks.

Reporting back.

Following up because I said I would. I changed one thing, left everything else alone, and waited the full interval before looking. It resolved, and I cannot prove which half of that did it.