Rails 4, RSpec, MySQL2 default value error on firs

I'm upgrading from Rails 3.2.14 to Rails 4. When running RSpec on my test suite in my Rails 3 branch, all tests pass. On the Rails 4 branch, however, I'm getting an error on the first instance only of creating a factory. The error reads:

ActiveRecord::StatementInvalid:
   Mysql2::Error: Field 'id' doesn't have a default value: INSERT INTO `of_of_measurements` (`aerobic_steps`, `calories`, `date`, `device_serial`, `distance`, `is_device_input`, `server_time`, `total_steps`, `user_id`) VALUES (15, 20, '2013-09-11 16:57:36', 'HJ1', 25.0, 0, '2013-09-11 16:57:36', 10, 1)

My factory looks like this:

factory :upload do
  sequence(:id) { |n| n }
  date Time.zone.now
  total_steps 100
  aerobic_steps 75
  distance 500.0
  calories 50
  sequence(:device_serial) { |n| "HJ#{n}" }
  is_device_input 0
  server_time Time.now
  person
end

I know it's generally not great to explicitly add id to factories, but given some legacy database issues I'm working with that require some bizarre associations, I've found it unavoidable here.

The full test suite includes several tests that require creating an upload factory, and what's really confusing me is that all other tests involving upload factories pass successfully. I'm pretty sure the issue is not with any specific test, because RSpec randomizes the order of the tests run and so a test that fails in one attempt will pass in the next (when it shows up later in the test suite).

I have a few other factories in which I'm doing the same sequence(:id) { |n| n } code, and none of them have this problem. I've also checked describe [table_name]; in MySQL and the id fields for all tables look the same: Default NULL, auto-increment.

Update Here's the of_of_measurements table configuration from a schema dump:

-- Table structure for table `of_of_measurements`
--

DROP TABLE IF EXISTS `of_of_measurements`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `of_of_measurements` (
  `id` bigint(20) NOT NULL,
  `user_id` bigint(20) NOT NULL,
  `date` datetime NOT NULL,
  `total_steps` int(11) NOT NULL,
  `aerobic_steps` int(11) NOT NULL DEFAULT '0',
  `aerobic_walking_time` int(11) DEFAULT NULL,
  `calories` int(11) DEFAULT NULL,
  `distance` float DEFAULT NULL,
  `fat_burned` float DEFAULT NULL,
  `hourly_steps` text COLLATE utf8_unicode_ci,
  `hourly_aerobic_steps` text COLLATE utf8_unicode_ci,
  `hourly_equip` text COLLATE utf8_unicode_ci,
  `hourly_event` text COLLATE utf8_unicode_ci,
  `is_device_input` tinyint(4) NOT NULL,
  `day_serial` int(11) DEFAULT NULL,
  `server_time` datetime NOT NULL,
  `device_serial` text COLLATE utf8_unicode_ci,
  `weight` float DEFAULT NULL,
  `clientversion` varchar(10) COLLATE utf8_unicode_ci DEFAULT NULL,
  `platform` varchar(10) COLLATE utf8_unicode_ci DEFAULT NULL,
  `hrm_duration` int(11) DEFAULT NULL,
  `hrm_max_hr` int(11) DEFAULT NULL,
  `hrm_avg_hr` int(11) DEFAULT NULL,
  `hrm_status` varchar(512) COLLATE utf8_unicode_ci DEFAULT NULL,
  `hrm_distance_readings` varchar(512) COLLATE utf8_unicode_ci DEFAULT NULL,
  `hrm_hr_readings` varchar(1024) COLLATE utf8_unicode_ci DEFAULT NULL,
  `walkMass` float DEFAULT NULL,
  `aerobicMass` float DEFAULT NULL,
  `aerobicCalories` int(11) DEFAULT NULL,
  `basalMetabolism` int(11) DEFAULT NULL,
  `walkCalories` int(11) DEFAULT NULL,
  UNIQUE KEY `id` (`id`),
  UNIQUE KEY `unique_measure` (`date`,`device_serial`(20),`user_id`),
  KEY `user_id` (`user_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
/*!40101 SET character_set_client = @saved_cs_client */;
/*!40103 SET TIME_ZONE=@OLD_TIME_ZONE */;

/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;

I found the answer to this issue. The legacy database did not set the id field to auto-increment. As a result, database_cleaner was having trouble cleaning the test suite db. The solution was to add self.primary_key = 'id' to my Upload model.