RadzenCrm stuck at Opportunity User Name

I am new to Radzen and just following the Create a CRM application. I have followed all the instruction to the tutorial, but I am stuck at the Opportunity Page where I turn UserId (GUID) to the User FirstName and LastName. If I change the Name $expand Value to Contact,OpportunitityStatus,User. I will get a constant spinning logo and when I open Chrome Dev tool, it would display the error. "Failed to load resource: the server :5000/odata/CRM/Contact,OpportunityStatus,User:1 responded with a status of 400 (Bad Request).

This could happen if some of the steps from the customize security article are not performed. Radzen's output window will contain an exception which tells more why the request has failed.

I don't think that is the case because I just redo the whole application again and it still giving that error. There could be an update to the Identity that is causing the code not to work. Please have someone redo the CRM and stop at the Opportunity and they will eventually get the same error as me.

I just followed the instructions from the tutorial but do not get any error. What is the exception stacktrace in Radzen's output window?

As a Radzen Professional user you can send us the server directory of your application to info@radzen.com? We will check what could have gone wrong.

This was more of Visual Studio mistake when creating the custom cs files where the namespace was wrong.
The problem is in the Opportunity.Custom.cs file - the casing of the namespace is wrong

namespace RadzenCrm.Models.CRM
{
public partial class Opportunity
{
[ForeignKey("UserId")]
public ApplicationUser User { get; set; }
}
}

It should be

namespace RadzenCrm.Models.Crm
{
public partial class Opportunity
{
[ForeignKey("UserId")]
public ApplicationUser User { get; set; }
}
}
Thanks for the help.