Yongnuo yn568ex compatibility with Z series

Hi all,

Is that true that the yongnuo yn568ex speed light and the Z series are not compatible?

I tried to use it recently on my Zfc but they seem not to correctly communicate over the hotshoe, and the pictures are all over exposed. The flash (in i-TTL mode) correctly set the focal length but it seems the body (in P or A mode) is unable to detect it and the aperture, speed and ISO are all set as for no flash. The trigger works fine and the flash activates so the result is an overexposed picture.

So the only way to use it is in a all-manual mode?

Or am I missing some important setting?

Thanks in advance!