I went to sleep and woke up about half past three in the night. We have had an Indian summer the last couple of days and the heat was unbearable. So of course I went about googling and thought I found the answer.
When turning the heel I needed to include both of the rounds of yarn that I had put around the slipped stitch. If you have never made an hourglass heel, read the instructions I linked to in the last post.
And now it turned out OK. Not gorgeous, but OK. And, at least on the one side.
On the other side I must have turned the stitches the wrong way, see below. But I have one more sock to go, so this time I considered the work good enough and did not frog it.