Issue Summary

This is reproducible on Data Center: (yes) 

Steps to Reproduce

1. Noticed this behavior in the Jira version 9.12.10 (it could be possible, other versions are also impacted)
2. Create a custom field of type Text Field (multi-line) and attach it to the screens of any project.
3. Set the renderer to the Wiki Style Renderer, by navigating to the Field Configurations page.
4. Create an issue in the same project. Fill some data in above custom field.
5. Once the issue is created, perform an Inline edit of the custom field and notice the attachment button is greyed out. The tool tip says - Attaching files isn't supported here. To attach files, open the issue in a different view.
   
6. If we check the same in Jira 9.1.1, the attachment button works fine there during inline edit.
   

Expected Results

Attachment button should not be greyed out during inline edit of the Custom field.

Actual Results

Attachment button is greyed out and adding attachment is not possible with inline edit.

Workaround

Click on Edit button of the issue, navigate to that same custom field and add attachment from there. Attachment button is not greyed out.