Peek and pop on anchors in an XHTML page

I haven't been able to get peek and pop to work on any XHTML page. Obviously this code will work for an HTML page:

<a href="//apple.com">apple</a>

But if it's served with Content-Type: application/xhtml+xml, the anchor won't respond to 3D touch. The exact same code served with Content-Type: text/html works tho. Is this a bug?

Peek and pop on anchors in an XHTML page
 
 
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