Essentially the placing of boats, armor stands, minecarts aren't detected as an individual signal strength of 14 as depicted by the latest article which says that the game event 'entity_place' this is incorrect as the game event and other relevant articles show that dispenser should be able to cause this event to occur. This still occurs with buckets of fish and variants.

If any of these actions are completed by the player as opposed to a dispenser they game event occurs which is why I believe that the game event not being detected when completed by a dispenser, is a bug