We have a client where PDFs are not attached to the email when creating emails from invoices and quotations. There is only a text, but PDF is missing in the paperclip and that X icon thing.
Print preview and printing the same invoice/quotation works.
Another interesting behaviour: every second (or so) time we create an email from the invoice via Invoice Create menu, the email created is with status "new", not "inspect" as it should be.

Client had version 8.5 2021-08-28, we upgraded to 8.5 2023-02-08, but it didn't help.
What else to do?