Unable to setup FortiLink from FortiManager

Hello,

I'm trying to setup FortiLink between a FortiGate and a FortiSwitch through FortiManager (5.4.2) and fail. I have noticed that although I set the addressing mode of the Fortilink interface to "Dedicated to extension device", when installing the config from FMG to FGT, this particular parameter does not pass to the FGT and the Fortilink fails. Has anybody experience in such configuration?

Thanks

Andreas