Until now I’ve successfully kept all of my save-editing stuff in a single folder on D-drive.
The latest installation of Horizon, for some reason unknown to me (and with a new icon), has installed itself somewhere completely separate on the hard drive rather than overwriting the existing version.
Taking all the files and just dumping them in the previous folder to overwrite what was already there seems to have worked… but why did the installer go and install a second copy in the wrong place anyway?