The last try check following in menu:
1 Turn on the menu. A: MOD MENU
2 Move across to the PHASE MENU choice on this level. G:PHASE MENU
3 Move down a level and then across to the UNLOCK ERR command.4:UNLOCK ERR
4 Move down a level and disable the unlock error. DISABLE
5 Save the change and turn off the menu.
The unlock error setting is stored in non-volatile memory, and does not change when power has been off or after a remote-interface reset
I found this in option menu manual, so give a try.
I think you are mixing this up with the older Agilent 33120A that had the vacuum fluorescent display (VFD)
This one is the 33220A with LCD and graphics display that does not have this menu
Or I am mistaken?
You are right, so if this menu is not available you can try it by SCPI.
It is not fix, but can be used like bypass to enable output.
PHASe:UNLock:ERRor:STATe {OFF|ON}
PHASe:UNLock:ERRor:STATe?
Disable or enable the function generator from generating an error if
the phase-lock is ever lost. The default is OFF. If the phase-lock is lost
and the error is enabled, a “Reference phase-locked loop is unlocked”
error is generated. The unlock error setting is not stored in non-volatile
memory. That is, the setting will be lost when the power is cycled. The
:STAT? query returns “0” (OFF) or “1” (ON)
Reference phase-locked loop is unlocked
The PHAS:UNL:ERR:STAT has been enabled (“on”) and the internal
phase-locked loop that controls the frequency is currently unlocked.
This error is most likely to occur when the external reference is out of
lock range.