Hi Joao,
Attachments are not currently supported for editing in the Inbox, they will not be displayed either. This includes images, audio, signature questions types. There are some workarounds to enable adding new attachments in a survey when using the Inbox, but it requires having a repeat in the survey and adding a new record to the repeat.
We have an enhancement to support images (attachments) in the Inbox, and is high on our priority list to support in the future release.
Phil.