Bees seem to have difficulty pathfinding to a beehive, (and presumably bee nest), if there are two beehives placed on top of each other.  In this scenario bees will actively pathfind to the upper hive, but will have difficulty pathfinding to the lower hive, preferring to attempt to enter the already full  of three bees upper hive, and very rarely succeed in entering the lower hive.  It should be noted that in this particular case, there is a campfire in the block space directly below the lower hive, so as to allow the upper and lower hives to benefit from the campfire smoke.  There are also a variety of crops, specifically beetroot, wheat, potatoes, and carrots to the left and right adjacent sides of the hives.  The growth stage of these crops however seems to have no effect on the pathfinding of the bees.  So, any quick fix would be greatly appreciated.  Thank you!