Well, I was intrigued - so I compared Tony’s modified version with the original - and there is a greyed out box in the citation number settings checked in the original and unchecked in Tony’s (see attached) – to uncheck that box, you need to first check the one above it (group citations), and then unckeck that second option (composite), then uncheck the grouped references again. This is a strange bug. When I did that on the original, it now correctly formats two consecutive citations with a comma and not a dash.