I am able to replicate this, and it’s impacting my app as well. You can replicate it easily in the react-router template. The code below does this:

Using <a> or react router Link does not work – it seems it has to be s-link to show the breadcrumb, but the nav is broken. @Anthony_Frehner
export default function Demo() {
return (
<s-page heading="Additional page">
<s-link slot="breadcrumb-actions" href="/app">
Home
</s-link>
Additional page content
</s-page>
);
}