Issue while setting up triggers for a field in embedded object

I am trying to setup a database trigger for an embedded object .

My Embedded Object is set up as :

"review_info" :{
      "in_review" : boolean,
       "date" : Date,
       .....
}

I am trying to run a database trigger, when a document is updated and in_review is set to true.

For that the query in my trigger configuration is set as ::

{
    "updateDescription.updatedFields" : {
          "review_info.in_review": true 
    }
}

So when I change the “review_info.in_review” manually from mongo data services (collections), the trigger is working fine, but if the same data is changed from client app (which is a flutter app with atlas device sync sdk (realm)), I am getting the error :

error in read messages loop: could not decode next message: 
failed to get reader: WebSocket closed: 
failed to acquire lock: context deadline exceeded

The funny thing is if i set up the query as :

{
    "updateDescription.updatedFields" : {
          "review_info":  {   "$exists" : true}
    }
}

The trigger works fine.