It's well-known that Marketo's pURL feature, out-of-the-box, has a fatal (and kinda fascinating) shortcoming. If someone has visited your site before — meaning either an anonymous or associated Munchkin session— then pURL-enabled pages aren't functional.
When there's an existing anonymous session, the server ignores the personalized part of the URL (the Marketo Unique Name
/JillSmith02 or Unique Code
/XYZPDQ) and serves up default/empty content.
On the other hand, if the person has never been to your site on their current device, pURLs work fine.
Unfortunately, then, pURLs work only for people who either [a] just got a new PC or phone or [b] have been living under a relative rock. Not exactly the widest audience! ☺