Solr - using _text_ catch-all field

I am trying to index a sample JSON document in my Solr core which is as follows

[
  {
    "ID": "1",
    "title": "Cooking Recommendations",
    "tags": ["cooking", "meetup"],
    "posts": [{
        "ID": "2",
        "title": "Cookies",
        "comments": [{
            "ID": "3",
            "content": "Lovely recipe"
          },
          {
            "ID": "4",
            "content": "A-"
          }
        ]
      },
      {
        "ID": "5",
        "title": "Cakes"
      }
    ]
  },
  {
    "ID": "6",
    "title": "For Hire",
    "tags": ["professional", "jobs"],
    "posts": [{
        "ID": "7",
        "title": "Search Engineer",
        "comments": [{
           "ID": "8",
           "content": "I am interested"
         },
         {
           "ID": "9",
           "content": "How large is the team?"
         }
        ]
      },
      {
        "ID": "10",
        "title": "Low level Engineer"
      }
    ]
  }
]

Now, I have updated my managed-schema.xml file to enable the _text_ catch-all field as I would want to make free-text queries without specifying the key against which the query string should be run.

This is how my schema looks

<field name="_root_" type="text_general" indexed="false" stored="true" docValues="false" />
<field name="_nest_path_" type="_nest_path_" />
<fieldType name="_nest_path_" class="solr.NestPathField" />

<field name="_text_" type="text_general" indexed="true" stored="true" multiValued="true"/>
<copyField source="*" dest="_text_"/>

The corresponding analyzer

    <fieldType name="_text_" class="solr.TextField" positionIncrementGap="100">
        <analyzer type="index">
            <tokenizer class="solr.WhitespaceTokenizerFactory" />
            <filter class="solr.WordDelimiterFilterFactory" generateWordParts="1" generateNumberParts="1" catenateWords="1" catenateNumbers="1" catenateAll="0" splitOnCaseChange="1" preserveOriginal="1" />
            <filter class="solr.StopFilterFactory" ignoreCase="true" words="stopwords.txt" enablePositionIncrements="true" />
            <filter class="solr.LowerCaseFilterFactory" />              
            <filter class="solr.SnowballPorterFilterFactory" language="German" />
            <filter class="solr.RemoveDuplicatesTokenFilterFactory"/>
        </analyzer>
        <analyzer type="query">
            <tokenizer class="solr.WhitespaceTokenizerFactory"/>
            <filter class="solr.WordDelimiterFilterFactory" generateWordParts="1" generateNumberParts="1" catenateWords="1" catenateNumbers="1" catenateAll="0" splitOnCaseChange="1" preserveOriginal="1" />
            <filter class="solr.StopFilterFactory" ignoreCase="true" words="stopwords.txt" enablePositionIncrements="true" />
            <filter class="solr.LowerCaseFilterFactory" />              
            <filter class="solr.SnowballPorterFilterFactory" language="German" />
            <filter class="solr.RemoveDuplicatesTokenFilterFactory"/>
        </analyzer>
    </fieldType>

With this config, the JSON documents gets indexed fine and I am able to run a query like title:"Cooking Recommendations" to retrieve the first JSON object alone. However, I am trying to run a free-text query without specifying the key title and just pass the query string to fetch the same results. I looked into the Solr documentation and see that I can achieve this with CopyField directive, however, if I just pass the string "Cooking Recommendations", I get no results.

I did see the core's schema and see that _text_ field is available. Not sure what I am missing here. Can someone guide me?

EDIT:

I am performing my queries using the Solr query UI which is as follows:

I am using /select as the request handler, passing the df as _text_. Still, it doesn't return the results I expect.

EDIT 2:

I tried using the Analysis tab as suggested below and see that it works fine there.