...ok, I asked Gary and he has no idea either.
The best I can guess is that Kevin Jenkins, who took over the Tide/Edit masters after Ruth Christie and Cathy Saunders passed away, dumped a bunch of unreleased material on the "Best of Tide Records" compilations he put up on Amazon Music and Deezer. Half of the tracks have no artist listed. Thanks to Gary's article, I was able to figure out a bunch of them, but this version of "Mystery of a Miracle" is clearly from the archive and not the version put out on the single. I think some folks ripped the "digital" version and put it on YouTube under Ruth's name, when it's clearly not the same version.
Basically, I don't think we'll ever know! Thanks to everyone here for trying, though.