Cosmos query does not extract and use partial hierarchical partition key

[ajcvickers]

Query, where Region is the top-level partition key:

    var customers = await context
        .Set<Customer>()
        .Where(e => e.Id == id && e.Region == region)
        .ToListAsync();

SQL:

info: 8/28/2024 12:14:24.244 CosmosEventId.ExecutedReadNext[30102] (Microsoft.EntityFrameworkCore.Database.Command) 
      Executed ReadNext (260.3355 ms, 2.79 RU) ActivityId='206d1672-4891-47f3-a378-742711a1261b', Container='SomeDbContext', Partition='None', Parameters=[@__id_0='0e2ba07d-e248-42a7-9ba2-08dcc6ad40f4', @__region_1='Europe']
      SELECT VALUE c
      FROM root c
      WHERE ((c["Id"] = @__id_0) AND (c["Region"] = @__region_1))

Repro

using (var context = new SomeDbContext())
{
    await context.Database.EnsureDeletedAsync();
    await context.Database.EnsureCreatedAsync();

    var id = new Guid("0e2ba07d-e248-42a7-9ba2-08dcc6ad40f4");
    var region = "Europe";
    var country = "UK";

    var customers = await context
        .Set<Customer>()
        .Where(e => e.Id == id && e.Region == region)
        .ToListAsync();
}

public class SomeDbContext : DbContext
{
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder
            .UseCosmos(
                "https://localhost:8081",
                "C2y6yDjf5/R+ob0N8A7Cgv30VRDJIWEHLM+4QDU5DE2nQ9nDuVTqobD4b8mGGyPMbIZnqyMsEcaGQy67XIw/Jw==",
                "EFDatabase")
            .LogTo(Console.WriteLine, LogLevel.Information)
            .EnableSensitiveDataLogging();

    protected override void OnModelCreating(ModelBuilder modelBuilder) 
        => modelBuilder
            .Entity<Customer>()
            .HasPartitionKey(e => new { e.Region, e.PrimaryCountry });
}

public class Customer
{
    public Guid Id { get; set; }
    public required string Name { get; set; }
    public required string PrimaryCountry { get; set; }
    public required string Region { get; set; }
}