I'm working on an Advanced Roadmaps plan that includes some custom fields. They are visible in the Basic view, but there is no "sort" icon for their columns, and they don't appear in the View settings > Sort by dropdown menu.
I've confirmed that these custom fields should be sortable - one is a single-line text field ("Text Field (single line)"), and the other is a user picker ("User Picker (single user)").
Any ideas on how to fix this?
Background info: