The Xbox does not use AMD's Platform Security Processor, they have their own custom controller on die with Microsoft hardware and their own custom BootROM. This custom security processor actually has its own bit of RAM entirely in the die and doesn't even go out to the DRAM at all.
But the million dollar question is, do they rotate the IV per block or do they opt for speed as AMD and Intel both did by deriving it from the address and thus are vulnerable to someone sniffing the bus? (Note that older Intel server hardware wasn't vulnerable in this way but tracking IVs slowed everything down so they did away with it.)
See the slide on Tony Chen's presentation about Xbox One security https://youtu.be/U7VwtOrwceo?t=843 and this video from the person who hacked the Xbox One https://youtu.be/FTFn4UZsA5U?t=299