I'd recommend testing from the iCloud push notification console just to make sure how it's getting sent is very similar to how your server would send it.

https://github.com/bradp-dev/ios-test-projects/tree/main/liveactivitiestest We ran this on the problem device but didn't seem to notice an issue with the PTS issuance (it worked). The pipeline for retrieving the PTS token is almost identical but as can be expected our app is also doing many other things in this time as well. I can try to start with our app and trim off things until it starts working or can you spot something clearly wrong in the current implementation?