SQL Server 2012 :: Sequence In A Table Instead Of Identity

I've started using a SEQUENCE in a table instead of an identity.

I seem to be experiencing problems of the sequence getting reset to a lower value periodically. Inserting will work on the table, producing the next bigint in the sequence as the primary key, for days and then all of the sudden duplicate primary key errors show up. When I check, the last primary key value in the table is higher than the current value of the sequence.

For example: right now I have primary key values 6000 through 7032 contiguously in the table, all of which were generated with the sequence. Suddenly I'm getting duplicate primary key errors. A quick check of the sequence shows it's at 7002, but the last inserted row has a primary key of 7032!

I'm populating this table in one place (in the application layer), leaving the primary key null, which allows the default constraint to get the next sequence.

When the problem shows up, I've reset the sequence to the higher number in the past and all is well for many days, then the problem occurs again.

The definition for the sequence is:

CREATE SEQUENCE [dbo].[IntegrationQueueSEQ]
AS [bigint]
START WITH 1
INCREMENT BY 1
MINVALUE 0
MAXVALUE 9223372036854775807
CYCLE
CACHE 50

The default constraint for the primary key on the table is defined as:

ALTER TABLE [dbo].[IntegrationQueue] ADD CONSTRAINT [DF_IntegrationQueue_IntegrationQueueID] DEFAULT (NEXT VALUE FOR [dbo].[IntegrationQueueSEQ]) FOR [IntegrationQueueID]