The first problem I faced was that my references were grouped, but I unchecked the “Use one number for references always cited together”, editing the JCTS style (Citations->Numbering).
Now I have another issue.
(The superscribe is ok.)
Guide example:
Pauling and co-workers 10,11
My output:
Pauling and co-workers 10-11
However, if the citations are not consecutive, I get the right output, something like:
The shipping version of this style uses the “Composite Citations” option. Please check with the editor of the journal to see if this feature is even needed anymore. The author instructions do not mention it.
If it is not needed you can fix the range issue by de-selecting the option “Use letters to separate grouped references”. If the option is greyed out, select “Use one number for references always cited together” and you can de-select the “letters” option. Make sure to save the style and to use the modified style in your paper.
The Composite Citations option indtroduced a bug that causes the ranges to not work properly when there are only two citations in the range. That is why you have to edit that portion of the output style.