PrincipalInfo.Current.IsPermitted() for anonymous users

Hello,

I defined couple of virtual roles and some permission types in the system I am working on. The virtual roles are there in order to assign permissions to the roles using Permissions for Functions. After doing these I can assign specific permissions for the user role. 

<virtualRolesaddClaims="true">       
    <providers>
        (Other Episerver roles)
        <addname="CustomRole"type="EPiServer.Security.MappedRole, EPiServer.Framework"roles="CustomRole"mode="Any" />
    </providers>     
</virtualRoles>

The virtual roles are assigned to CurrentPrinciple under runtime by adding a Claim to the user. The claim is defined as:

public static ClaimsIdentity CustomRole => new ClaimsIdentity(new[]
{    new Claim(ClaimTypes.Role, "CustomRole")
});

And added to user by 

var user = EPiServer.Security.PrincipalInfo.CurrentPrincipal as ClaimsPrincipal;
user?.AddIdentity(CustomRole);

I can then query the database with 

PrincipalInfo.Current.IsPermitted(CustomPermissions.Permission)

and it works as expected as long as I am logged in as Episerver admin. However, IsPermitted function returns always false if the user is anoynmous even though the user has the claim "CustomRole". 

Am I missing something in order to use IsPermitted function for anonymous users?

Thanks in advance.