Is anything connected to SPDIF?

Regards
Daniel Fuchs
RME

That means the SPDIF Input is Locked, but not Sync'd.  If you want to use your Fantom-G w/o Pops and Clicks over SPDIF, you'll need to get your Master/Slave clocking figured out.  What other Digital gear is in the system?

You'll want to make one unit the "Master".

I'm not familiar with the Fantom, but if it is capable of locking/syncing to an external input (be it SPDIF or BNC Wordclock), then I'd leave the FF-UC as the Master (Internal Clock), and feed a SPDIF or BNC signal into the Fantom as a clock reference - and set the Phantom to lock to this input accordingly.  The FF-UC and/or the DAW Application will control the system's sample rate in this case (Fantom should follow along).

If the Fantom CAN'T sync to an external clock, then leave it as the Master, and change the FF-UC to lock to SPDIF Input.  The Fantom will then control the sample rate for your system.