NEST Suggester errors

Here is the (pruned) response from the server using the Phrase Suggest.

{
shards = null,
    aggregations = {},
    aggs = {},
    profile = null,
    suggest = {},
    took = 0,
    timedOut = false,
    terminatedEarly = false,
    scrollId = null,
    hitsMetadata = null,
    numberOfReducePhases = 0,
    total = 0,
    maxScore = 0,
    documents = [],
    hits = [],
    fields = [],
    serverError = {
        error= {
            headers= {},
            rootCause=[
                {
                    causedBy= null,
                    metadata= {
                        ...
                    },
                    reason= "suggestion does not support [TEXT]",
                    stackTrace= null,
                    type= "parsing_exception"
                }
            ],
            causedBy= null,
            metadata= {
                ...
            },
            reason= "suggestion does not support [TEXT]",
            stackTrace= null,
            type= "parsing_exception"
        },
        status= 400
    },
    isValid = false,
    apiCall = {
        auditTrail=[
            {
                ended= "2019-05-13T16=35=38.29013Z",
                event= 9,
                exception= null,
                node= {
                    clientNode= false,
                    deadUntil= "0001-01-01T00=00=00",
                    failedAttempts= 0,
                    holdsData= true,
                    httpEnabled= true,
                    id= null,
                    ingestEnabled= false,
                    isAlive= true,
                    isResurrected= false,
                    masterEligible= true,
                    masterOnlyNode= false,
                    name= null,
                    settings= {},
                    uri= "..."
                },
                path= "...",
                started= "2019-05-13T16=35=37.664307Z"
            }
        ],
        debugInformation= "Unsuccessful low level call on POST= /_searchresults/searchresult/_search?pretty=true&typed_keys=true # Audit trail of this API call= - [1] BadResponse= Node= http=//lb-xxxxxxxxxxxxxxx.south-centralus.cloudapp.azure.com=9200/ Took= 00=00=00.6258230 # OriginalException= Elasticsearch.Net.ElasticsearchClientException= Request failed to execute. Call= Status code 400 from= POST /_searchresults/searchresult/_search?pretty=true&typed_keys=true. ServerError= Type= parsing_exception Reason= "suggestion does not support [TEXT
        ]" # Request= { "suggest"= { "person - suggest"= { "TEXT"= "For", "PHRASE"= { "field"= "TITLESUGGEST", "size"= 3 } } } } # Response= { "error" = { "root_cause" = [ { "type" = "parsing_exception", "reason" = "suggestion does not support [TEXT
        ]", "line" = 4, "col" = 15 } ], "type" = "parsing_exception", "reason" = "suggestion does not support [TEXT
        ]", "line" = 4, "col" = 15 }, "status" = 400 } ",
        deprecationWarnings=[],
        httpMethod= 1,
        httpStatusCode= 400,
        ...
            failureReason= 1,
            request= {
                accept= "application/json",
                allowedStatusCodes=[],
                basicAuthorizationCredentials= {
                    password= "...",
                    username= "..."
                },
                ...
                node= {
                    clientNode= false,
                    deadUntil= "0001-01-01T00=00=00",
                    failedAttempts= 0,
                    holdsData= true,
                    httpEnabled= true,
                    id= null,
                    ingestEnabled= false,
                    isAlive= true,
                    isResurrected= false,
                    masterEligible= true,
                    masterOnlyNode= false,
                    name= null,
                    settings= {},
                    uri= "..."
                },
                onFailureAuditEvent= 9,
                onFailurePipelineFailure= 1,
                pathAndQuery= "...",
                pingTimeout= "00=00=02",
                pipelined= true,
                postData= {
                    disableDirectStreaming= true,
                    type= 4,
                    writtenBytes= "e..."
                },
                ...
            },
            ...
        },
        ...
    },

    ...

}