While trying to fill pdfs I noticed that I've been getting pdfcpu: textfield missing "DA" error. I looked into some threads on the internet regarding Default Appearance and found that changing the font to auto in adobe acrobat resolved this issue, unfortunately this fix isn't apt for me as I want to specify the font with which the pdfs should be filled. Can you given me some context on why this is the case and how to resolve this issue other than setting the font to auto.