Supress author does not work where title is used in place of author (Anglia Ruskin University style)

AlexT25

I am making a custom CSL style based upon the "Anglia Ruskin University - Harvard" style. For films (and a few other item types) both the Anglia style and my style require the title of the film to be used in place of the author for inline citations (the director of the film features after the date in the bibliography). For example (where "Bram Stoker’s Dracula" is the title of the film) the inline citation would be:

(Bram Stoker’s Dracula, 1992)

The "Anglia Ruskin University - Harvard" style's implementation of this seemed to work fine so I left that part of it untouched when making my style. However I have now noticed that the suppress author option does not work for films (and other items where the title is used in place of the author). When the suppress author box is checked I would expect the above citation to appear as just "(1992)", like what happens with other item types, but at present the citation remains unchanged. This issues appears to be present in both the "Anglia Ruskin University - Harvard" style, and my style based upon it.

Is this a limitation in CSL / Zotero, or is it something which should work but the implementation of the "Anglia Ruskin University - Harvard" style (and thus my style) is preventing it from working correctly?

Thanks for any help