Quote from FCOM 1 :
GO AROUND (GA) :
Go-around mode combines the speed reference system (SRS) vertical mode with the GA TRK lateral mode.
ENGAGEMENT CONDITIONS :
Setting at least one thrust lever to the TOGA detent engages both SRS/GA TRK modes,
if :
– The flaps lever is at least in position 1, and
– The aircraft is in flight, or
– The aircraft has been on ground for less than 30 seconds (AP disengages and can be re-engaged five seconds after lift-off).
The FMA displays “SRS” and “GA TRK” in green.
Ok, that all makes sense, however if this is so, then why doesn't the auto flight engage the go around mode when you select MAN TOGA airborne after an engine failure after take off ? All that happens is the setting of MAN TOGA thrust with no change to the other modes.