Desperate! Laravel Eloquent Issues: 'Column not found' on Relationship After Update. Any Fixes?

I am absolutely pulling my hair out right now! I've been stuck for what feels like an eternity—hours, seriously—trying to fix a critical bug that popped up after a recent Laravel package update. My app is basically dead in the water because of this, and I'm getting desperate for a solution.

The problem is a 'Column not found' SQLSTATE error. Specifically, it's happening when I try to access a relationship using Eloquent. The weirdest part is that the column project_id clearly exists in my users table, and this exact relationship was working perfectly fine before I ran composer update. It's a standard belongsTo relationship on the User model connecting to a Project model.

This issue started immediately after updating a few core Laravel packages, including the framework itself. I'm suspecting some subtle change in how Eloquent handles relationships or eager loading post-update. It's almost like it's trying to find the foreign key on the wrong table or constructing the query incorrectly, leading to these frustrating Eloquent relationship errors.

Here's the error log snippet I'm seeing:

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'users.project_id' in 'where clause' (SQL: select * from `users` where `users`.`project_id` = 1 and `users`.`project_id` is not null)

And this is the relevant part of my User model and how I'm trying to access it:

public function project() {
    return $this->belongsTo(Project::class);
}
// ...
$user = User::find(1);
$user->project->name; // This line throws the error when trying to access the relationship

I've already tried everything I can think of: clearing all caches (config, route, view, application), running php artisan migrate:refresh (even though it's not a migration issue), double-checking all my column names and model relationships, and ensuring my foreign key constraints are correct. Nothing seems to work, and the error persists.

Has anyone else encountered similar Laravel Eloquent issues post-update? I'm completely stuck and urgently need some advice or pointers on what might be causing this.