OnTrac recently re-designed their website a few months ago and it seems to have broken synchronization for the app as well. I've had about ~5 packages since the change via OnTrac and all of them have never successfully synced. The "Show in browser" button in the overflow menu still works fine, it's just pulling delivery status updates that's broken. Here is one of these packages as an example to help debug:
Please let me know if you need anything else from me and thanks in advance!