How to reproduce:
Open Email with file attached (pdf).
Try to click on the file directly or klick on the little arrow to open the menu "open"/"download" and try to open the file.

Actual Outcome:
When opening the email (either via the little arrow/menu or directly on the link) no content is displayed. Only when the file is downloaded it works.

Expected Outcome:
the content of the file is displayed when trying to open it.

This problem occurred on ios.