Missing assembly reference—but I believe the package is properly referenced

Question

When I register the following using declaration:

using Microsoft.AspNetCore.Identity.UI;

I am getting the following error:

'UI' type or namespace name does not exist in namespace 'Microsoft.AspNetCore.Identity' (missing an assembly reference?)

Everything looks right to me. I'm including a <PackageReference> to the Microsoft.AspNetCore.Identity.UI NuGet package. But the error persists.

How do I troubleshoot this?

My .csproj

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>netcoreapp3.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.App" />
    <PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="3.1.4" />
    <PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="3.1.3" />
    <PackageReference Include="Microsoft.AspNetCore.Identity.UI" Version="3.1.4" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="3.1.3" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SQLite" Version="3.1.3" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="3.1.3" />
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="3.1.3" />
    <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
    <PackageReference Include="Microsoft.AspNetCore.Authentication" Version="2.1.1" />
  </ItemGroup>
</Project>

And my AssemblyInfo.cs:

using System;
using System.Reflection;

[assembly: Microsoft.AspNetCore.Identity.UI.UIFrameworkAttribute("Bootstrap4")]
[assembly: System.Reflection.AssemblyCompanyAttribute("ESporcum")]
[assembly: System.Reflection.AssemblyConfigurationAttribute("Debug")]
[assembly: System.Reflection.AssemblyFileVersionAttribute("1.0.0.0")]
[assembly: System.Reflection.AssemblyInformationalVersionAttribute("1.0.0")]
[assembly: System.Reflection.AssemblyProductAttribute("ESporcum")]
[assembly: System.Reflection.AssemblyTitleAttribute("ESporcum")]
[assembly: System.Reflection.AssemblyVersionAttribute("1.0.0.0")]

Answer 1

In NuGet package

change this:

Microsoft.AspNetCore.Identity.UI Ver.5.0.1

to:

Microsoft.AspNetCore.Identity.UI Ver.3.1.10