The users can't create features in the epics slide-out panel without add/create epics permission.
- Navigate to Administration -> Roles -> Select a role from the drop-down -> Enable portfolio epics toggle(Under Portfolio -> Manage). Make sure just the Epic main toggle is turned on.
- Enable All Feature permissions(Under Program -> Manage).
- Go to the epics grid and select any epic.
- Scroll down to the features section.
There is an option to quick add the feature in the epics slide-out panel.
There is no option to quick add the feature in the epics slide-out panel.
As a workaround enable add epics permission. Another option is to add the feature from the feature grid or create button in top-right corner.