Project roles cannot be selected as recipients in filter subscriptions is correct.

This is because filter subscriptions accept individual users or groups as recipients and do not allow project roles. Project roles are not addressable recipients so they will not appear in the recipients list even when they exist in the project.

She is not assigned to that project role is incorrect because who is assigned to a role does not change whether the subscription feature exposes roles as a recipient type. The absence is due to the feature not supporting project roles rather than role membership.

She lacks the Manage group filter subscriptions global permission is incorrect because that permission governs who can manage group subscriptions and does not alter which kinds of entities can be selected as recipients. Having or not having that permission would not make project roles selectable.

She does not have the required project permission to view the project is incorrect because missing project view permission affects access to project data but it does not cause project roles to appear in the recipients list. The underlying limitation is that filter subscriptions do not support selecting project roles.

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