OK, I think I’ve figured out what the issue is there - the search result items with no (visible) link are pointing to component that have no ‘Display Title’ set. If you don’t want the component to have a Display Title, you can workaround this issue by enabling the Search Extension setting Search Results > Use Title Fallback:
Then, in the component, set a title here:
And that then will be used as the ‘link title’ in the search results