What you were expecting to happen, and what actually happened?
Using a Mythic troop would give a higher bounty multiplier than an Epic troop. It gave less (23x vs 25x).
What are the steps to make it happen again?
Swap a mythic troop (Parrot) for an Epic troop (Half Mane)
Do you have any screenshots or video you want to share with us so we can see the problem? Attach them to your post!
For future reference, every time there is a bounty weekend, the troop you get from the shop is the bounty captain. The devs are encouraging you to spend gems (or Orbs of Ascension) to get that troop to mythic and enjoy the x12 bonus.
In case someone unaware wonders: Using two copies of Bounty Troops or Captains won’t work to give more bonuses to score. The multipliers are counted for unique troops.