Rasa core executing wrong utterance

Hello community, I’ve trained the dialogue model with the stories bellow (among many others). The NLU correctly identify intent and slots, but the core component is not behaving as expected.

## info gold flex
* Card_type{"card_type", "creditcard", "creditcard_type" : "gold", "refund_type" : "flex"} 
    OR Card_type{"creditcard_type":"gold", "refund_type" : "flex"}
   - utter_info_creditcard_gold
   - utter_info_creditcard_flex

## info gold flex
* Card_type{"card_type", "creditcard", "creditcard_type" : "silver", "refund_type" : "flex"} OR Card_type{"creditcard_type":"silver", "refund_type" : "flex"}
  - utter_info_creditcard_silver
  - utter_info_creditcard_flex

The scenario is the following:

1st step: Ask the question: what is silver flex?

NLU identifies intent ‘Card_type’ and slots “creditcard_type=silver” and “refund_type=flex”. Then, dialogue utters correctly the 2 messages specified in utter_info_creditcard_silver and utter_info_creditcard_flex respectively

2nd step: Now Ask the question: what is gold flex?

NLU identifies intent ‘Card_type’ and slots “creditcard_type=gold” and “refund_type=flex”. Then, core gives the wrong answers. I’ve experienced 3 cases:

  1. responds the fallback message (I don’t understand …)
  2. utter gold only
  3. utter flex only

My training configuration is:

policies:
  - name: "MemoizationPolicy"
    max_history: 3
  - name: "KerasPolicy"
    featurizer:
    - name: MaxHistoryTrackerFeaturizer
      max_history: 4
      state_featurizer:
         - name: BinarySingleStateFeaturizer
   - name: "FallbackPolicy"
     nlu_threshold: 0.75
     core_threshold: 0.3
     fallback_action_name: "utter_default"

I’m also using

augmentation_factor : 0
use_story_concatenation: True
remove_duplicates: True
debug_plots: False

Any insight would be greatly appreciated.