Printing Royal Mail Labels

Hope someone can help.

In the past, when we purchase Royal Mail postage labels in bulk through Amazon, we are able to print them as a PDF is opened in another tab. Also, a zip file is downloaded. In the last week, the PDF does not appear and we have to use the ZIP file, which means printing each label individually which is incredibly time consuming. Has anyone else had this issue and if so, did you find a way to rectify it?

Thank you in advance.

Dennis