For a deeper look into our Eikon Data API, look into:
Overview | Quickstart | Documentation | Downloads | Tutorials | Articles
Attachments: Up to 2 attachments (including images) can be used with a maximum of 512.0 KiB each and 1.0 MiB total.
According to the question, I assume that you are unable to launch the Codebook application.
If yes, please contact the Eikon or Workspace support team directly via MyRefinitiv to verify and solve the problem.