One IEnumerable with 1 item mysteriously becomes empty after I query a second IEnumerable

var pkeys= qry.GetTableColumns(tableName)
    .Where(col => col.Kind == Column.ColumnKinds.PartitionKey)
    .Select(col => new PropertyGenerationModel(col));
var ckeys= qry.GetTableColumns(tableName)
    .Where(col => col.Kind == Column.ColumnKinds.Clustering)
    .Select(col => new PropertyGenerationModel(col));

using Cassandra.Mapping;
using CassandraClient.Config;
using CassandraClient.Metadata.Models;
namespace CassandraClient.Metadata;

public class MetaDataQueries(SessionOptions options)
{
    public IEnumerable<Column> GetTableColumns(string tableName)
    {
        var session = SessionFactory.GetSession(options);
        Mapper mapper = new(session);
        var columns = mapper.Fetch<Column>(
            $"select * from system_schema.columns where table_name = '{tableName}' and keyspace_name = '{session.Keyspace}' allow filtering;");
        return columns;
    }
}