The connector may be defective. You would know that to be the case if you have had this problem since buying the motherboard.
The connector may have become damaged in use. You would know this to be the case if the problem has only recently made itself evident. (This, of course, does not eliminate the possibility that the manufacturer used a substandard part.)
The connector, itself can be replaced, but most motherboard manufacturers are using audio I/O clusters, now, instead of discrete connectors, to save on PC board real estate.
A single connector is actually a simple repair--just a matter of minutes to replace--however, most consumers are not prepared to be able to do these kinds of repairs. An audio I/O stack is more involved, making the situation worse on the consumer-side of things.
This may be one of those times when you test the customer service capabilities of the motherboard manufacturer / vendor.