Whenever you have the RegexFeaturizer in your NLU pipeline, Rasa is looking for matching candidates of your defined regular expressions in the text. However, Rasa will not just extract them as entities, but will create features, e.g. word matches regex for account or not. Those features will be added to the features used for the CRF (model to extract entities). Thus, you need to add some examples to the NLU data, so that the CRF can learn that those features are relevant to determine whether a word is an entity or not.
So, maybe double check if the RegexFeaturizer is in your pipeline and try to add some more examples to the NLU data.