**How to reproduce**
Clickhouse server 20.13.1.5273
```
CREATE TABLE default.test
(
`key` UInt32,
`ts` DateTime CODEC(DoubleDelta, LZ4),
`db_time` DateTime DEFAULT now() COMMENT 'spout-ignore' CODEC(DoubleDelta, LZ4)
)
ENGINE = MergeTree
PARTITION BY toStartOfTenMinutes(db_time)
ORDER BY (key, ts)
TTL db_time + toIntervalHour(3)
SETTINGS index_granularity = 8192, merge_with_ttl_timeout = 3600, min_rows_for_compact_part = 1000000, min_bytes_for_compact_part = 200000000, in_memory_parts_enable_wal = 0;


INSERT INTO test(key, ts) SELECT number % 1000, now() + intDiv(number,1000) FROM numbers(500);

SELECT * FROM test;
500 rows in set. Elapsed: 0.003 sec.

DETACH TABLE test;

ATTACH TABLE test;

SELECT * FROM test;

0 rows in set. Elapsed: 0.002 sec.
```

**Expected behavior**
Clickhouse would flush parts on disk.
{
    LOG_INFO(log, "Waiting mutation: {}", file_name);
    {
        auto check = [version, this]()
        {
            if (shutdown_called)
                return true;
            auto mutation_status = getIncompleteMutationsStatus(version);
            return !mutation_status || mutation_status->is_done || !mutation_status->latest_fail_reason.empty();
        };
        std::unique_lock lock(mutation_wait_mutex);
        mutation_wait_event.wait(lock, check);
    }
    
    std::set<String> mutation_ids;
    mutation_ids.insert(file_name);
    auto mutation_status = getIncompleteMutationsStatus(version, &mutation_ids);
    try
    {
        checkMutationStatus(mutation_status, mutation_ids);
    }
    catch (...)
    {
        tryLogCurrentException(__PRETTY_FUNCTION__);
        throw;
    }
    LOG_INFO(log, "Mutation {} done", file_name);
}
void StorageMergeTree::mutate(const MutationCommands & commands, ContextPtr query_context)