Forwarding already sent email

Recently I wanted to forward an already sent email to another recipient. In the first try the email got transmitted, but without attachment. In another try the email got transmitted with the attachment (PDF), but the name of the file was changed to: ‘noname.pdf’.

K-9 Mail 5.806 on Android 10, Security Patch level August 1, 2021
Can you check this please?
Thank you