Thanks for the tip that the original author might have used hyperlink targets rather than bookmarks to set up the cross-references. (they don't point to numbered headings)
I've looked at the table again, with the Apply Styles panel open. All the links, including the one I've set up, appear to be using the Hyperlink style – but mine persists in looking different. Ctrl+space to clear posible overrides makes no difference. Where should I look next?