Modulation of freq control in VCO 1 should let you use LFO 1, or LFO 2 to mod the pitch of VCO 1.
However, if in the Modulation Page you set any source and a destination that uses LFO1 AM or LFO 2 AM, it disables/overrides any modulation that is set up on the front panel using LFO 1 or 2.
To reproduce:
Use preset Init Voice 1.
Turn Modulation knob in VCO 1 to 'Freq'. You'll hear vibrato.
in Modulation page, set a Source to anything e.g. wheel, set Destination to LFO 1 AM, and vibrato will stop. LFO mod on front panel has been disabled and can now only be used via the Modulation Page.
Vibrato via front panel control comes back on as soon as LFO 1 AM is deselected as 'Destination'.
Strangely, this will happen even when the Modulation Page is switched off.
I believe the function of the Modulation Page is to add modulation in addition to what's happening on the front panel, not to override it. This does not happen for e.g. LFO 1 FM or other Destination types.
I suspect this is a bug.
This is in standalone mode, on Mac.
Cheers Jeff