When playing through Midsummer Seduction in Hentai Heroes, or Merc Season in Comix Harem if you pass over a tier when battling you will not be able to claim it, and will not receive the reward for it.
Example being that if you enter Merc Season at Tier 16, and win enough to become Tier 18, you do not get to select the Tier 15 option to claim the relevant reward. In this scenario, the +40 energy you should have received has not been rewarded.
This bug is present in both Hentai, and Comix