Samsung issues a statement on compatibility of 3rd party accessories with Note 3 on KitKat
Samsung immediately reacted on reports that 3rd party accessories are not working after Android KitKat arrived for the Samsung Galaxy Note 3. The update has begun checking for the ID chip, and if it isn't there, the accessory won't work. A number of XDA threads say this even includes the Spigen S-View flip cover, of all things. The problems likely lie with other accessories, too, and could present a nuisance for users that already bought them.
There is a way to skip the ID check, if you root the Note 3, but a lot of people wouldn't do that. Here's Samsung's official statement of the matter (translated from German):
To ensure a pleasant and smooth user experience with Samsung products for our customers, we recommend that only original accessories from Samsung are to be used. Of course, customers can continue to rely on third-party accessories. The full functionality of our devices and accessories, however, can only be ensured with genuine Samsung components, since only in this way it is certain that the equipment and accessories are perfectly matched. A correlation between the Android version 4.4 and the supposed incompatibility of third-party accessories does not exist.