Dumb question, but have you dried drawing it without flower in it? Because if you get the same taste, it is your tempest (clean it again before doing that). And if the taste only happens with flower, it must be the flower or the tempest in combination with the flower
Be careful with the head, don't soak the visual indicator. And if you do, shake the iso out after taking it out and gently blow it with a hair dryer. Afaik that's what the mad heaters website recommends