When I change the spacing from “Centers” to “Gap between”, the objects nearer not further apart. It looks like it is setting the outer gap not the inside gap. Is that correct?
I realised the reason which is that I was using negative distances. Perhaps that is implemented in CC intentionally that way.
The Array tools were tested with, and work as expected, with positive values.
Other products (such as Lightburn) work with negative distances. I would suggest that CC either be enhanced to support negatives or have an audit put into the code to prevent it.