Carole: I am using PSP Ultimate 2023. I had forgotten about saving as PSD. When I went back into the file, no work had been saved, only the original page.
Something similar happened once before in PSP 2021, and I used a workaround to get a JPG for the forum. When I opened the same file in 2022 when it became available, there was no problem.
Gremlins. That’s what it is. Gremlins.