There is a workaround. Attach the file to the invoice. Then at the top click “Old layout” then “ switch layouts” then submit. Then scroll to the bottom and click the box “attach to email”. Don’t send from this layout. Rather click save and close. Then switch the layout back to the new layout and send to the customer. This will send the invoice with the attachment in the new format. Kind of a pain but luckily I only have to send a few invoices with attachments so it works for me until the engineers get this glitch fixed.