I took a quick look at the logic for the shield and everything looks like it should be mitigating properly. We'd like to hear reports from some other players as well but for the moment nothing looks out of the ordinary.

The shield can be removed through damage like Nekro's shield, however with the 95% damage reduction it would be fairly difficult to do that unless the pet was very low level and the amount of damage the shield can take is significantly lower than expected.