If when using a laptop / PC and try Chrome, don't use the app or mobile browse, then if it's still not possible for you to manually edit and change that tracking number contact eBay Customer Services, they can do this for you, I recommend contacting them tomorrow when the lines first open at 9 a.m. there's more chance of Dublin answering.
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 between 8 a.m. to 10 p.m. on weekdays.
9 a.m. to 6 p.m. on weekends.
As said, I recommend contacting CS very first thing in the morning, when the lines first open, as there's more chance of Dublin answering.
@simocheetha0
