Issue
Idea - attachments aren't saved when an idea is created.
Cause
The Submit UI and possibly Save UI buttons are missing the latest version.
To quickly identify if this is the issue, the Submit UI Action script field should contain the following on line 3:
var ideaRec = current;
Resolution
Contact ServiceNow Technical Support in order to ensure the UI Actions contain the expected update from the [Demand Management] plugin.
Provide this Knowledge Article in your initial description of the issue.