Error when querying on search_as_you_type subfields (._2gram, ._3gram)

Hi there. I've been trying to use search_as_you_type for an autocomplete solution. I've mapped a field as the "search_as_you_type" type, however when trying to query on the field, the ._2gram and ._3gram field, as described in the documentation (Search-as-you-type field type | Elasticsearch Reference [7.12] | Elastic) I get an error:

    {
      "error" : {
        "root_cause" : [
          {
            "type" : "query_shard_exception",
            "reason" : "failed to create query: class org.elasticsearch.index.mapper.SearchAsYouTypeFieldMapper$SearchAsYouTypeAnalyzer cannot be cast to class org.elasticsearch.index.analysis.ReloadableCustomAnalyzer (org.elasticsearch.index.mapper.SearchAsYouTypeFieldMapper$SearchAsYouTypeAnalyzer is in unnamed module of loader java.net.FactoryURLClassLoader @60f21960; org.elasticsearch.index.analysis.ReloadableCustomAnalyzer is in unnamed module of loader 'app')",
            "index_uuid" : "-B_u7gl-Qqaxumkt5v7D9Q",
            "index" : "werkzaamheden_v3"
          }
        ],
        "type" : "search_phase_execution_exception",
        "reason" : "all shards failed",
        "phase" : "query",
        "grouped" : true,
        "failed_shards" : [
          {
            "shard" : 0,
            "index" : "werkzaamheden_v3",
            "node" : "FLpy4hJrRkWsc0lco0QteA",
            "reason" : {
              "type" : "query_shard_exception",
              "reason" : "failed to create query: class org.elasticsearch.index.mapper.SearchAsYouTypeFieldMapper$SearchAsYouTypeAnalyzer cannot be cast to class org.elasticsearch.index.analysis.ReloadableCustomAnalyzer (org.elasticsearch.index.mapper.SearchAsYouTypeFieldMapper$SearchAsYouTypeAnalyzer is in unnamed module of loader java.net.FactoryURLClassLoader @60f21960; org.elasticsearch.index.analysis.ReloadableCustomAnalyzer is in unnamed module of loader 'app')",
              "index_uuid" : "-B_u7gl-Qqaxumkt5v7D9Q",
              "index" : "werkzaamheden_v3",
              "caused_by" : {
                "type" : "class_cast_exception",
                "reason" : "class org.elasticsearch.index.mapper.SearchAsYouTypeFieldMapper$SearchAsYouTypeAnalyzer cannot be cast to class org.elasticsearch.index.analysis.ReloadableCustomAnalyzer (org.elasticsearch.index.mapper.SearchAsYouTypeFieldMapper$SearchAsYouTypeAnalyzer is in unnamed module of loader java.net.FactoryURLClassLoader @60f21960; org.elasticsearch.index.analysis.ReloadableCustomAnalyzer is in unnamed module of loader 'app')"
              }
            }
          }
        ]
      },
      "status" : 400
    }

This is the query:

    GET werkzaamheden_v3/_search
    {
      "query": {
        "multi_match": {
          "query": "wass",
          "type": "bool_prefix",
          "fields": [
            "omschrijving",
            "omschrijving._2gram",
            "omschrijving._3gram"
          ]
        }
      }
    }

This is the part of the mapping that contains that field and the settings

     "omschrijving": {
        "type": "search_as_you_type",
        "analyzer": "my_dutch_analyzer", 
        "search_analyzer": "my_search_analyzer"
      },
      "trefwoorden": {
        "type": "text"
      },
      "urn": {
        "type": "text"
      }
    }
      },
      "settings": {
    "index": {
      "routing": {
        "allocation": {
          "include": {
            "_tier_preference": "data_content"
          }
        }
      },
      "number_of_shards": "1"
    },
    "analysis": {
      "analyzer": {
        "my_dutch_analyzer": {
          "type": "custom",
          "tokenizer": "standard",
          "filter": [
            "lowercase",
            "dutch_stemmer",
            "dutch_stop"
          ]
        },
        "my_search_analyzer": {
          "type": "custom",
          "tokenizer": "standard",
          "filter": [
            "lowercase",
            "synonyms"
          ]
        }
      },
      "filter": {
        "dutch_stop": {
          "type": "stop",
          "stopwords": "_dutch_"
        },
        "dutch_stemmer": {
          "type": "stemmer",
          "language": "dutch"
        },
        "synonyms": {
          "type": "synonym",
          "synonyms_path": "analysis/synonym.txt",
          "updateable": true
        }
      }
    }
      }
    }

Does anyone have an idea of what is going wrong? This is in kibana, using elastic 7.11.1.