In the last month I have tried to pay for goods/services from checkout in several different seller's web pages and it won't work.  I get a popup screen with a spinning circle and nothing happens; I am not redirected to Paypal.  Then the popup disappears and I cannot proceed in the web-site and have to close it, restart and pay by card.

Note; the payment is NOT being declined or blocked - it simply isn't working.  A separate payment to an eBay seller went through last night without any issues.

Any ideas?