A couple of times I have had packages sent from China to the UK by Yanwen. When I enter the tracking reference in the Deliveries app, it says "status information not available". It continues to display the same message even when the package has been delivered. If I enter the reference in a different app, or use a tracking website, I see tracking information.
Example tracking reference: UH768244376YP
Tracking website tried: ship24.com
This site, and a different tracking app that I tried, both currently display "Order processed by shipper 12 September 2023".
My phone won't let me paste into this question, so I can't add the URL here, I hope this will be enough info.
I saved the info file from the "report a problem" option in the app, but can't see a way to attach it here.