The '/users/count' Endpoint from Red Hat Single Sign-On (RH SSO) is having a different behavior than the one expected

Issue

Having an user with the following representation:

{
    "username": "example.user",
    "firstName": "Example",
    "lastName": "User",
    "email": "example@user.com",
}

And calling the endpoint:

/users/count?search=ex us

I expect result to be 1, however it's 0.