7.9rc E-Mails without headers?

I like the new e-mail client but unfortunately, on our test system no headers are shown: all the header fields (From:, To: etc.) are empty.
I will try to add a screenshot but unfortunately, the “Add File” button doesn’t work on my Mac (neither in Chrome nor in Safari).

After importing the e-mail, the headers are shown.

(Please fix your forum settings so that the “Add File” button works again - I tried it on my Mac and also using Chrome on a PC)