See if you can manually add the tracking numbers you used here:
- Go to "Orders Paid & Dispatched"
- Click on "View order details"
- Within the "Postage" section there's a small dropdown arrow next to "Track Package" - click on that.
- Click on the "Add tracking" option
- A box will come up with the current tracking number . Delete that and replace it with your tracking.
You may need a laptop / PV and not the app or mobile browser, they're quite limited in their functions, use Chrome too, that seems to work well.
If the above doesn't help you'll need to contact eBay Customer Services:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
@moronaroca