I've seen e-mails from quite a few people reporting that they're having trouble leaving feedback for sellers they've bought items from, so I'd be inclined to say that it's yet another problem that eBay need to get to grips with and sort out. However, as there has been no update from eBay as to when this problem is likely to be put right what you could do in the meantime would be to log out of eBay UK and log in to one of the other sites, such as www.ebay.com (the American version of eBay). If you can leave feedback via one of the overseas sites but can't leave it whilst logged into the UK site then it's almost certainly a problem with eBay UK that eBay haven't got around to sorting out yet.
