Executing 4 stored procedures (using .NET 8 + EF Core) always stops due to a transaction timeout after approx. 15 minutes although the transaction scope timeout is set to 1 hour! In addition, the command timeout of the DBContext is set to 45 minutes.

Why does it fail after 15 minutes? Do I need to set another (timeout) setting?

Code (executed in a MediatR request handler):

    private static readonly string logLineStartedExecutingMethod = "Started executing method {MethodName}";
    private static readonly string logLineFinishedExecutingMethod = "Finished executing method {MethodName} - {RecordCount}";
    
    using var trans = new TransactionScope(TransactionScopeOption.RequiresNew, new TimeSpan(1, 0, 0), TransactionScopeAsyncFlowOption.Enabled);

    _logger.LogInformation(logLineStartedExecutingMethod, "UspTestA");
    var resultA = await _procedureRepository.UspTestAAsync(default, cancellationToken);
    _logger.LogInformation(logLineFinishedExecutingMethod, "UspTestA", resultA?.ToString() ?? "0");

    _logger.LogInformation(logLineStartedExecutingMethod, "UspTestB");
    var resultB = await _procedureRepository.UspTestBAsync(default, cancellationToken);
    _logger.LogInformation(logLineFinishedExecutingMethod, "UspTestB", resultB?.ToString() ?? "0");

    _logger.LogInformation(logLineStartedExecutingMethod, "UspTestC");
    var resultC = await _procedureRepository.UspTestCAsync(request.UserName ?? "Onbekend", default, cancellationToken);
    _logger.LogInformation(logLineFinishedExecutingMethod, "UspTestC", resultC?.ToString() ?? "0");         

    _logger.LogInformation(logLineStartedExecutingMethod, "UspTestD");
                
    // ERROR!!! Transaction timeout after approx. 15 minutes
    
    var resultD = await _procedureRepository.UspTestDAsync(default, cancellationToken);
    _logger.LogInformation(logLineFinishedExecutingMethod, "UspTestD", resultD?.ToString() ?? "0");

    trans.Complete();

Exception

    System.Transactions.TransactionException: The operation is not valid for the state of the transaction.
 ---> System.TimeoutException: Transaction Timeout
   --- End of inner exception stack trace ---
   at System.Transactions.TransactionState.EnlistPromotableSinglePhase(InternalTransaction tx, IPromotableSinglePhaseNotification promotableSinglePhaseNotification, Transaction atomicTransaction, Guid promoterType)
   at System.Transactions.Transaction.EnlistPromotableSinglePhase(IPromotableSinglePhaseNotification promotableSinglePhaseNotification, Guid promoterType)
   at System.Transactions.Transaction.EnlistPromotableSinglePhase(IPromotableSinglePhaseNotification promotableSinglePhaseNotification)
   at Microsoft.Data.SqlClient.SqlInternalConnection.EnlistNonNull(Transaction tx)
   at Microsoft.Data.ProviderBase.DbConnectionPool.PrepareConnection(DbConnection owningObject, DbConnectionInternal obj, Transaction transaction)
   at Microsoft.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at Microsoft.Data.ProviderBase.DbConnectionPool.WaitForPendingOpen()
--- End of stack trace from previous location ---
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternalAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternalAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenAsync(CancellationToken cancellationToken, Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.FromSqlQueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(AsyncEnumerator enumerator, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.FromSqlQueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at CBS.IHG.EHOConnector.adapters.Data.StoredProcedures.DbContextExtensions.SqlQueryAsync[T](DbContext db, String sql, Object[] parameters, CancellationToken cancellationToken)