If we insert the following record to a collection ```javascript db.classes.insert({     name: "Class A",     students: [       {         firstName: "Joe",         middleName: "Harry",         lastName: "Bar"       } ,       {         firstName: "Mary",         lastName: "Molly"       } ,       {         firstName: "Katie",         middleName: "Morgan",         lastName: "Smith"       }     ]   }) ``` Then run the following aggregation pipeline ```javascript db.collection.aggregate([   {     "$project": {       studentIndex: {         "$indexOfArray": [           "$students.middleName",           "Morgan"         ]       }     }   } ]) ``` We'd expect that the following is returned ```javascript [   {     "studentIndex": 2   } ] ``` however the following is actually returned ```javascript [   {     "studentIndex": 1   } ] ``` As you can see the index is off by 1.   https://mongoplayground.net/p/pCmXbXUkBOo