Multiple checklists

Add a checklist: select + (Create new checklist) at the top of the panel. It starts as New Checklist.
Rename: select the checklist's title, type a new one, and press Enter.
Delete: select the trash icon (Delete checklist) in the checklist's header. The first checklist on an issue can't be deleted, and deleting can't be undone.
Tab view: in the panel's ••• menu, select Enable tab view to show each checklist as a tab with its own progress count. The app remembers the choice for that issue.