Does anybody manage to get a dot leader in the toc in Clarke and Custom CSS?

Theming
1

I tried the following standard syntax without luck:
a[href]::after { content: leader(".") target-counter(attr(href), page) !important}

I tried on pressbooks.pub. I added the above line to the new Custom CSS. No sign of any dots in the toc.

I start to wonder if it is a custom CSS bug or if prince version on pressbooks.pub has a bug.