UI fails to load bucket insights in 6.5.x compat mode

n_0:2021-05-06T22:57:24.099+00:00 INFO CBAS.messaging.CCMessageBroker [Executor-2:ClusterController] Received message: ExecuteStatementRequestMessage(id=4, from=f750356b1afc692acc66eab7a74c419c): <ud>SELECT   ds.DataverseName,   ds.DataverseName || '.' || ds.DatasetName AS datasetFullyQualifiedName,   decode_dataverse_display_name(ds.DataverseName) AS dataverseDisplayName,   ds.DatasetName AS id,   TRUE AS isDataset,   ds.BucketName AS bucketName,   ds.ScopeName AS scopeName,   ds.CollectionName AS collectionName,   ds.BucketDataverseName as bucketDataverseName,   ds.`Filter` AS `filter`,   ds.LinkName,    ds.DatasetType,    concat2(', ', (select value FieldName || ' ' || (          CASE WHEN lower(FieldType) = 'int64' THEN 'BIGINT'               ELSE upper(FieldType) END) || (          CASE WHEN NOT IsNullable AND NOT IsMissable THEN ' IS NOT UNKNOWN'               ELSE '' END)        from t.Derived.Record.Fields)) AS TypeString,  ( SELECT       idx.IndexName,       idx.SearchKey,       idx.SearchKeyType     FROM       Metadata.`Index` AS idx     WHERE idx.IsPrimary = false       AND idx.DatasetName = ds.DatasetName      AND idx.DataverseName = ds.DataverseName) AS indexes,    ds.ExternalDetails.Properties AS externalDetails FROM   Metadata.`Dataset` AS ds left join Metadata.Datatype t on  ds.DataverseName = t.DataverseName and t.DatatypeName = ds.DatatypeName WHERE   (ds.BucketName IS NOT missing OR  ds.DatasetType = 'EXTERNAL')UNION ALL SELECT   dv.DataverseName,   decode_dataverse_display_name(dv.DataverseName) AS dataverseDisplayName,   TRUE AS isDataverse,   ( SELECT       l.Name     FROM       Metadata.`Link` AS l     WHERE       l.DataverseName = dv.DataverseName) AS links FROM   Metadata.`Dataverse` AS dv WHERE   dv.DataverseName != 'Metadata' UNION ALL SELECT   DataverseName,   Name,   IsActive,   `Type` as LinkType,   TRUE as isLink FROM   Metadata.`Link`;;</ud>

n_0:2021-05-06T22:57:24.114+00:00 INFO CBAS.translator.QueryTranslator [QueryTranslator:17f2ca68-e7b7-4c1b-8218-c5c08393d00d] ASX1079: Compilation error: function Default.concat2@2 is not defined (in line 1, at column 434)

n_0:org.apache.asterix.common.exceptions.CompilationException: ASX1079: Compilation error: function Default.concat2@2 is not defined (in line 1, at column 434)