Nah. Definite case of pebcac; it was the receiver, not the sender, that was at fault. https://stream.jeremycherfas.net/2019/somewhere-along-the-line-i-seem-to
Somewhere along the line, I seem to have lost a rather crucial line from the <HEAD>. Now, I hope it has returned.
If it has, please accept my apologies for spamming micro.blog.
So have I. And this time I am going to resist the temptation to ping the site to which I am replying.
I've been doing this for more than a month, and it works just fine.