MongoDB updatemany with arrayfilters does not update

Question

I got this document in a collection

{ 
    "_id" : ObjectId("1234"), 
    "title" : "Some Company", 
    "assignedPackages" : [
        ObjectId("2345"), 
        ObjectId("3456"), 
        ObjectId("4567")
    ]
} 

and this updateMany

db.getCollection("companies").updateMany(
    {  _id: ObjectId("1234"), "assignedPackages": ObjectId("2345")},
    { $set: { "assignedPackages.$[elem]" : ObjectId("5432") }}, // , "updatedAt": "$$NOW"  
    { arrayFilters: [ { "elem": ObjectId("2345") } ] }
)

When I run it it acknowledges the run and says 0 matched and updated. What am I doing wrong?