Thank you for your post, and I apologize for the late response.
I know some time has passed, so I don't know if you have found a resolution. If not, before anything else, update to FileMaker Server 14.0.2.
I am unable to test as I don't have a non-FileMaker supported certificate. I have sent all of your information including the screenshot to our Development and Testing departments for review. When I receive any feedback, I will let you know.