Hello, 

I am very new to mongo, so please forgive me if I am misusing the query syntax, but I have this situation that is either a bug or somebody please tell me how to correctly do it instead. Thank you.

I am trying to find documents where any or all nested array elements must contain at least the values provided. This can normally be achieved easily with the $all operator. For example here:

[
  {
    "words": [ "Hello", "World", "!"],
    "wordArrays": [
      ["Hello", "World", "!"],
      ["The", "Sun", "Shines"]
    ]
  }
] 

The query 

{words: {$all: ["Hello", "World"]}}

 correctly matches because both are contained and 

{words: {$all: ["Hello", "I do not exist"]}} 

 does not match. So far so good.

If you attempt the same for the nested arrays this stops working altogether. 

{"wordArrays.0": {$all: ["Hello", "World"]}} 

The above does not match. I have found Stackoverflow questions about why on nested arrays all the operators start to fail but no one ever can explain why and they just use $elemMatch. But I do not know how I would translate my "all values must be in the array" to an $elemMatch. How I would say

1. ANY of the wordArrays must contain "Hello" and "World" -> would match
2. ALL of the wordArrays must contain "Hello" and "World" -> would not match the data

I have prepared this little playground with the data in the hopes somebody knows how to achieve this.
https://mongoplayground.net/p/WSM2OGh-5vk

I would prefer if this could be solved all within the Find() stage, but if operations like this suddenly require the aggregation pipeline I am fine with that too.

My approach for ANY match does not return any matches, and I do not understand why 

{wordArrays: {$elemMatch: {$all: ["Hello", "World"]}}} 

I read it as wordArrays: does any element match: array contains "Hello" and "World". And that should have matched the document

Thank you!