Using RTC 3.0.1.1, and customizing my Project Area.
I found that hidden presentation for severity is not respected in the inline editor.
The problem seems to be related to the order of section configured in the process configuration.

Steps I used:
1. Create a project from Scrum template (should be reproducible with any OOTB)
2. In the Process Configuration tab, navigate to the Editor Presentation. Select 'com.ibm.team.workitem.web.inline'
3. Expand the 'Default' > 'Details' section (this is for defect type).
4. Double click on Severity (Enumeration) presentation. Select to hide if empty, hide on creation, and hide in all defect workflow states
5. Add a new section to the Default type. Slot = None
6. Move this new section to list before the Details (layout slot: Left) section
7. Save change

8. Create a new defect
9. Create a new query to list all the defects
10. Run the query in the WebUI
11. From the result list, click on the Edit icon in the Action column to edit the defect created in step#8.
expected: severity is NOT displayed
observed: severity is displayed

removing / adding the empty section before the Details section causes the issue not to show up / show up.

Is this a bug?