Filter does not active when using configUrl

Versions details

Spec created on Swagger 2.0 specification version. I've tested Swagger UI 3.9.2 and 3.1.0, both on Docker, with the same results. Google Chrome 64.0.3282.167 (Versão oficial) 64 bits on openSUSE Leap 42.2 64-bit.

Configuration

{
    "url": "https://raw.githubusercontent.com/OAI/OpenAPI-Specification/master/examples/v2.0/json/petstore.json",
    "filter": true,
    "docExpansion": [
        "none",
        "list",
        "full"
    ],
    "validatorUrl": null
}

?configUrl=https://....json

Expected Behavior

With this configuration, if I don't use configUrl but pass all parameters as query parameters, a text field is available to filter the tags. The expected behaviour is that the filter field to be available when using the filter option, using or not configUrl.

Current Behavior

The filter option looks like to be ignored.

Context

We are starting to document our APIs with Swagger and some use cases will make really good use of the filtering option. Actually some users have expressed their preference for the old version filtering style, as shown in http://editor2.swagger.io, using tags.