Thank you. I tried QBO support last week. We did a Glance screen-share session. The rep said she was sending my issue to a higher "tier" and that I would get an email from them, but I have not heard anything since then. She had me sign in to a QBO demo company and try attaching a PDF in the register there, and the same thing happened: instead of displaying the PDF in a new browser tab, a dialog opened to save the file. So:

• The problem does not appear to be a corruption of my company file, since it did the same thing with the demo company file.
• The problem does not appear to be in the browser, since it does the same thing with Chrome and Safari.
• The problem does not appear to be with the operating system or my computer, since it does the same thing on two different machines, one a Mac and the other running Windows 11.
• The problem is not confined to the checking register. New attachments to vendor profiles do the same thing, as do recent files in the attachment list, accessed through Settings.
• It's not just PDFs. I tried a PNG and it did the same thing, so it does not appear to be related to my system's default handling of PDFs. Are there any settings in QBO that govern how attachments are handled? I have not changed anything.

I have a case number. Should I request another call-back and give them that?

Meanwhile, the PDFs that I need to attach so that our records are complete keep piling up...