I can add custom fields to almost all screens, but I'm unable to add a custom field to the screen appears on 'Assign' button. (snapshot attached for reference)
In our organization, we track requests through support groups/teams, and when a team member assigns a ticket to another person, they also change the support group to the relevant one. However, in the Assign tab, only "Assignee" and "Comment" fields are visible.
Either, support group field should be made visible, or the entire button should be hidden to prevent the team from clicking on it.

