Is sorting on Text/String field no longer available in 5.x?

Elastic Stack Elasticsearch
3

I switched to sort by keyword and that sorted out the issue. Is this field now autogenerated? It got created without me specifying anything with field name "keyword". As for the fields I specified, they just don't get added in the mapping. This is my mapping:

{
                "strings": {
                    "match_mapping_type": "text",
                    "mapping": {
                        "type": "text",
                        "fields": {
                            "raw": {
                                "type": "keyword",
                                "ignore_above": 256
                            },
                            "english": {
                                "type": "text",
                                "analyzer": "english"
                            }
                        }
                    }
                }
            }