I'm trying to replicate this. I tried using a type=3 rover link (keyword destination), but it seemed to go through OK (followed the HTTP headers).
Then I tried a type=4 link (Custom URL destination) via the ePN Link Generator. Same thing - seemed to work OK.
But my tests were pretty quick, just with eBay US. ... Are you referring to a problem during the 301 hopping between rover servers that we often see in the headers for non-US ePN programs?
I wanna replicate this. Tell me what to do.
...On an unrelated note, while during the tests above I was surprised to see Flo, the Progressive lady, being advertised directly next to the eBay logo up top. That's a pretty novel UI/advertising move!
[Some Handy Aggregated Reference Info for ePN Affiliates and eBay Developers]