Edited object/document not saving properly on MongoDB in MERN app - node.js

Question

I'm building a MERN application where blog posts are created and edited, and comments to blog posts can be added and edited. When a blog post is added or edited everything works as expected, and comments are added as expected as well. But when a comment is edited, it doesn't save properly in the database. It gets saved across the session because of rendering functions I added in the react files, but when the app is reloaded the comment edit is gone and the comment is back to how it was originally. When I look at the database, I notice the edited comment is added by itself, but its original copy inside of the comment is not edited. I'm assuming there is an issue with how I'm configuring the model schemas, and/or I'm not accessing the blog post document directly. But I don't know exactly what the issue is despite what I've tried.
Below are two editComment functions that I've tried in the server side express/mongoose files, the first is successful at adding the edited comment to the database but it's failing to access and edit the original one inside of the blog post. The second one is taking into consideration the object id of the post the comment is in, but this just sends a 500 error and goes nowhere. I also have the blog post and comment schemas provided to give a better idea of where the issue may lie.
try {
let newDate = new Date();
let date = newDate.toDateString();
let post = req.params.postid;
const { title, content } = req.body;
const updatedComment = await Comment.findByIdAndUpdate(req.params.commentid, {title, date, content, post});
await updatedComment.save();
res.status(200).json(updatedComment);
} catch (error) {
res.status(404).json( {message: error.message} );
}
}
try {
const { title, content } = req.body;
let newDate = new Date();
let date = newDate.toDateString();
let post = new mongoose.Types.ObjectId(req.params.postid);
const postDoc = await Post.findById(post).lean().exec();
const comment = await Comment.findById(req.params.commentid).exec();
comment.title = title;
comment.date = date;
comment.content = content;
comment.post = post;
const updatedComment = await comment.save();
res.status(200).json(updatedComment);
} catch (error) {
res.status(500).json( {message: error.message} );
}
}
var PostSchema = new Schema({
title: {type: String, required: true, maxLength: 300},
date: {type: String, required: true},
content: {type: String, required: true},
comments: [{type: Object, required: true}],
})
module.exports = mongoose.model('Post', PostSchema);
var CommentSchema = new Schema({
title: {type: String, required: true, maxLength: 300},
date: {type: String, required: true},
content: {type: String, required: true},
post:{type: Schema.Types.ObjectId, ref:"Post", required: true},
})
module.exports = mongoose.model('Comment', CommentSchema);