Usually, if an asset that doesn’t exist is causing errors such as this, it means that there is another asset that is referencing that missing asset. This means that when it tries to load that asset, it tries to load anything that it is referencing. Could you make sure that there aren’t any assets that would be referencing this?
Also, try using the Fix up Redirectors in Folder option when right-clicking a folder in the Content Browser. That can sometimes clear up issues such as this.