Triggers don't work on grids spawned via trigger>action>spawner mechanics if the spawn group has [RivalAiSpawn:true] and [FactionOwner:Nobody].
I tested all sorts of triggers, everything works fine as long as you have a faction tag in [FactionOwner:Value], but as soon as you change it to Nobody (which is one of its legitimate options, search FactionOwner here) all triggers stop activating.
It's worth noting that the triggers still show up as being loaded and enabled when you use /MES.Info.GetGridBehavior, they simply never activate.