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):