Cannot Select Sub-Header in Timeline: Field Is Greyed Out

Problem

You’re trying to add a sub-header to Timeline, but the field you want to use is grayed out.

Solution

Here are the three most likely reasons that field is grayed out:

1. Field type isn’t supported
   The app only allows List (Single-Select), Multi-Select, or Team Member fields as headers.
   If the field you’re trying to use is a Freeform Text, Numeric, or Date field, it will be grayed out because the roadmap can't group that data into clear lanes.

2. Multi-select / Team Member conflict
   You can’t use two Multi-Select or Team Member fields at the same time for your headers.
   If your Primary header is already set to a Multi-Select or Team Member field, the app grays out all other Multi-Select and Team Member fields for the Sub-header to keep the visualization readable.

3. Jira integration limitations
   If you’re syncing from Jira, some complex or read-only fields may not be available as headers.
   These fields can still appear on the item card, but the app can’t use them to pivot or structure the Timeline layout.

Quick check for you: Look at the icon next to the field in your All Data table view.