Attachment erased from paperclip after using task "show attachment again"

[ChristianeMussmacher]

Hoccer version 3.3.30

reproducible with the following attachment types:

• contact
• image from pasteboard
• video from pasteboard

Steps to reproduce:

1. Select one of the above-named attachment types
2. click on selected attachment and chose "show attachment again" from dialogue
3. use back button
4. attachment is no longer selected