Hi there, @OldToad.

I know that this hasn't been easy experience.

Allow me to share some information on how you can avoid downloading the  file after providing an attachment to your invoice. 

Instead of using a PDF file, I suggest that you attach JPG which is an image file type .

I also recommend visiting this link to learn how to keep books and transactions more organized: Attachments in QuickBooks Online. If you need some reference is using our other features or answers to frequently asked questions, you can visit our Help Articles page.

Please comeback here if you need further assistance with the attachments feature. I'll be right here to help share more insights and information about it.