Empty popup window over paypal popup

-- HikaShop version -- : 6.6.0 [2609141704]
-- Joomla version -- : 6.1.3
-- PHP version -- : 8.3.33
-- Browser(s) name and version -- : Opera One(version: 135.0.5973.92)
-- Error-message(debug-mod must be tuned on) -- : No error

Hi,
since the update to HikaShop Business 6.6.0 [2609141704] our paypal credit/debit option is popping up a window to complete the paypal part. However, an additional empty popup is appearing over the top of it. It can be moved out of the way (see attached image). How can remove that and returning to running the form on the same pages as the paypal payment method selection button?

Thanks,
Ian and Stu