Just been reviewing the permalinks options, along with some ‘lite’ plugins and this is not really the issue, I don’t think . . .
I can change the URL to eg www.my-site/topics/my-new-page using the standard Wordpress admin. for category slugs and permalinks.
The URL is fine, but when it displays in the Shapely header, the html span tags on the slug are displayed eg Category: span<> tagsHistoryspan</> tags like in the demo Shapely site . . . which makes me think it’s an issue with the theme itself. This issue has been raised earlier in this forum too.
Also on Colorib demo site Markup Archives - Shapely Demo
Hope you can help