Can't seem to increment a nested value in mongoose

I can't seem to increment a nested value in mongoose. I have tried multiple revisions that I have found online and none seem to work. I am using mongodb version 3.2 and mongoose 4.9.5.

This project is a forum. There is a thread with a "posts" property which is an array. Each post has a "like" property which has a "users" property for each person who liked that post, and a count property that should increment with each update. Here is my model:

const threadSchema = mongoose.Schema({  
title: {type: String, required: true},
date: {type: Date, default: Date.now},
author: {type: String, required: true},
content: {type: String},
posts: [{
    content: {type: String, required: true},
    user: {type: String, required: true},
    created: {type: Date, default: Date.now},
    likes: {
        users: [String],
        count: {type: Number, default: 0}
    },      
    comments: [{
        comment: {type: String},
        user: {type: String},
        created: {type: Date, default: Date.now},
        likes: {type: Number, default: 0}
    }]
}]
});

And here is my update code. It is pushing to the posts.likes.users array just fine but wont increment:

Threads.findOneAndUpdate({"posts._id": req.body.postId}, {"$push": {"posts.$.likes.users": user}}, {$inc: {"posts.$.likes.count": 1}})

I have also tried these versions:

 {"$inc": {"posts.likes.count": 1}}
 {"$inc": {"posts.$.likes.count": 1}}
 {"$inc": {"posts.$.likes.$.count": 1}}

Thanks.

via DGwang