See if this below helps, you may need a laptop / PC and try Chrome, not the app or mobile browser to manage this:
- 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.
If this doesn't work, you could contact eBay Customer Services they may be able to add this for you, again if not, your payout will be held for a minimum of 14 days.
This is the easiest and quickest way to contact eBay Customer Services, for a Call Back option.
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
Lines open 8 a.m. - 10 p.m. on weekdays
9 a.m. - 6 p.m. on weekends.
Automated agents will be available on chat outside of the above hours.
I recommend contacting CS first thing in the morning as there's more chance of Dublin answering.
@juliei13