You are not alone with this issue.
Seems it could be an issue with this new Buyers Protection Fee rules, as eBay's tracking for one, is slow to update, and if Royal Mail have not scanned the items correctly would delay that payout.
However, as most of your items are under a £10 in value level, so will be exempt from the necessity to add a tracked service, see eBay's latest announcement here:
We’ve also heard your feedback and understand that shipping costs are particularly top of mind for low price items. When you’re selling a single item for £10 or less, and it’s sent untracked, funds will now be available 24 hours after you receive positive buyer feedback. This will be live by the end of February.
Yep, I know, most buyers do not leave feedback, and I would never usually recommend this, but sending the buyer a polite message, asking if they would kindly leave some feedback, explaining with eBay's new rules, payouts from sales are not released until a buyer leaves feedback. I would though recommend only sending one message, otherwise sending more, it could look like harassment.
Think most buyers then would leave some ?
@18sand