The Falcon Administrator has created a new prevention policy to apply to the "Servers" group;...

The most likely issue for not being able to apply a new prevention policy to the “Servers” group is that the “Servers” group already has a policy applied to it. A prevention policy is a policy that defines the prevention capabilities and settings for the Falcon sensor on a host. You can create and assign custom prevention policies to different hosts or groups in your environment. However, you can only assign one prevention policy per host or group at a time. If a host or group already has a prevention policy applied to it, you cannot apply another prevention policy to it unless you remove or replace the existing one2.

References: 2: Cybersecurity Resources | CrowdStrike