ASP.NET Core MVC Display Templates not rendering

Question

I'm trying to use display templates to change how a DateTime is rendered but the default template is always being used.

The model:

public class ProgressDetailViewModel : MemberDetailBaseViewModel
{
    // <snip>
    public DateTime? CurrentJourneyStartDate { get; set; }
}

Display template:

@using DateTime.Extensions;
@model Nullable<System.DateTime>

@if (Model.HasValue)
{
    <span class="form-control">@Model.Value.ToSpecificTimeZone().ToString()</span>
}
<span>Hello from display template</span>

The view:

@Html.DisplayFor(m => m.CurrentJourneyStartDate)
@Html.DisplayFor(m => m.CurrentJourneyStartDate, "DateTime")

The display templates seem to be in the correct location:

However the date is always rendered using the default template. I have downloaded the sample from the above link and this works fine when I edit it to include a DateTime display template.

Environment:

• .NET 6
• ASP.NET Core MVC
• Runs in Docker on Alpine linux

Why aren't the display templates being picked up?