c# – Visual Studio doesn’t import custom templates

I’ve created a VS template using VS 2026, but no matter what I do, it doesn’t appear in the Add New Item menu.
I used the Export Template feature. It stated that it couldn’t export, but the export file was generated nonetheless.

Files:

Assets Db Entity.zip:
-AssetsDbEntity.cs
-MyTemplate.vstemplate
-_PreviewImage.png
-_TemplateIcon.ico

AssetsDbEntity.cs:

/*
   @Date                 : 01.01.$year$
   @Author               : Stein Lundbeck
   @Description          : null
   @Version              : 1.0.0.1
   @Latest               : 01.01.$year$
*/

using SLT.Assets;

namespace $defaultnamespace$;

public interface I$safeitemname$ : IAssetsDb
{

}

public class $safeitemname$ : AssetsDb, I$safeitemname$
{

}

MyTemplate.vstemplate:

<VSTemplate Version="3.0.0" xmlns="http://schemas.microsoft.com/developer/vstemplate/2005" Type="Item">
  <TemplateData>
    <DefaultName>AssetsDb.cs</DefaultName>
    <Name>Assets Db Entity</Name>
    <Description>Create an entitty implementing IAssetsDb</Description>
    <ProjectType>csharp</ProjectType>
    <SortOrder>10</SortOrder>
    <Icon>__TemplateIcon.ico</Icon>
    <PreviewImage>__PreviewImage.png</PreviewImage>
  </TemplateData>
  <TemplateContent>
    <References />
    <ProjectItem SubType="" TargetFileName="$fileinputname$.cs" ReplaceParameters="true">AssetsDbEntity.cs</ProjectItem>
  </TemplateContent>
</VSTemplate>