Pvz Heros Quarterly Bonus + Sappy Place bug

The opposing wall knight was placed down a sap fling, which created a sappy place environment below my grave robber, who had 0 attack. I used quarterly bonus to give the grave robber 4 attack and do a bonus attack to kill the sapp fling in the same lane, but it only did 2 damage. Not sure why, so I used my Dolphinado, which bounced the very much alive sap fling. The next turn, the wall knight placed the sapp fling, and made a sappy place environment under my Teleportation Zombie, who's attack went down to zero. I had another Quarterly Bonus and used it to make my Teleportation Zombie's attack to 4, and do 4 damage to the opposing Starch-Lord with 4 hp, and this time it only did 3 damage. I lost :|

Tldr: If in a Sappy place environment, your quarter bonus will leave the plant at 1 hp instead of killing it.