On further use, looks like my other templates (import, develop, metadata) have also disappeared. These were all there a few days ago, so did not get lost in the upgrade. I did have a pre-upgrade backup, and restored them all from that, once I figured out how to get the backup catalog to open using LR5, which was still on the computer (to avoid converting that catalog to LR6, which I thought at that time might result in the same loss of temps). So all temps & presets are restored now, but I have no idea what I did to lose them to begin with.