If on the Royal Mail Track & Trace site, and eBay's Tracking, both do not show delivery, you will need to wait 14 days for that payout to be released.
One thing to be aware of, that is, Royal Mail tracking is sometimes not in sync with eBay's tracking, and the latter is the most important for releasing a faster payout, that is, 2 days after the delivery date.
If you have found your tracking has not updated, therefore holding back your payout, contact eBay Customer Services, provide the tracking showing delivery, ask if they can kindly release your payout now as 48 hours have passed the delivery date.
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.
I recommend contacting CS very first thing in the morning, when the lines first open, as there's more chance of Dublin answering.
@doorsafe