Why is my newly created rule not working?
Most of the time, the reason is that you created a private rule instead of an organization one.
Personal rules will only trigger on private conversations, and organization rules only on conversations linked to your organization (shared).
If the conversation has a color banner, it is linked/shared with your organization.
If you want some rules to apply to private and shared conversations, you will need to duplicate personal rules as organization rules or vice versa.