meta_search NoMethodError when using fields_or_fields structure query

I am using meta_search. The following gives correct results:

User.search({:first_name_contains_any => ["peter", 开发者_StackOverflow"john"]}).all
User.search({:last_name_contains_any => ["wong", "lee"]}).all

But the following does not work and throws NoMethodError:

User.search({:first_name_or_last_name_contains_any => ["peter", "something"]}).all

Does anyone has idea on it? Am I missing something..?

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I cannot replicate this problem with meta_search 0.9.10. It works fine for me.