_You need to Synchronize the clocks.
_You must set Cubase to send MIDI CLOCK OUT to the MOXF. It does not send clock commands until you set that up.
_You must set the MOXF to slave to external clock. The MOXF will follow the tempo you set in Cubase.
_You must set the MOXF to receive transport control from Cubase. Setting the sequencer control will allow the MOXF to start/stop along with Cubase.

Here's how:

In Cubase:
Go to TRANSPORT > PROJECT SYNCHRONIZATION SETUP... > MIDI CLOCK OUT > DESTINATION = Yamaha MOXF6/MO8-1 (port 1)

On the MOXF:
Press [UTILITY]
_ Press [F6] MIDI
_ Press [SF3] SYNC
_ Make sure that "MIDI Sync" is set to "EXTERNAL" and "SeqCtrl" (Sequencer Control) is set to IN/OUT

In Cubase you must also setup to receive audio from the MOXF using the Yamaha Steinberg USB Driver.

Please see our articles on Basic Audio Recording parts I, II, III:
Basic Audio Recording Part I

Huge thanks Bad Mister. It worked!:)