Hey Wayne,
Thanks for Joining us on the UK Community Page for QuickBooks.
We do have a new investigation into some issues with invoices, but the error message is different than you attached - We'd encourage you to "Export to PDF" the invoice - You'll then be able too attach this to your emails as an attachment, rather than replying on the in-system methodology.
With the error message being different, I'd be inquiring if they have an alternative browser to the one this has loaded up on, so we can see if it's local to that browser - the SS is Safari, can we try Chrome, Firefox?
