Value of union type attribute is not loaded on form

[nallwhy]

Describe the bug

Value of union type attribute is not loaded on form

defmodule Post do
  use Ash.Resource, data_layer: Ash.DataLayer.Ets, domain: Domain

  attributes do
    uuid_primary_key :id
    attribute :title, :string, allow_nil?: false
    attribute :content, Content, allow_nil?: false
  end

  actions do
    defaults [create: [:title, :content], update: [:title, :content]]
  end
end

# new post with content
post =
  Post
  |> Ash.Changeset.new()
  |> Ash.Changeset.change_attributes(%{
    title: "title",
    content: %{"type" => "normal", "body" => "body"}
  })
  |> Ash.create!()

# create form for update
post
|> AshPhoenix.Form.for_update(:update, forms: [auto?: true])
|> to_form()

But value of input element of form[:content][:body] is empty.

To Reproduce

https://gist.github.com/nallwhy/bab128b393e4a1db5ae514ea06e57a31

initial value of content is %{body: "body"}, but it's not loaded on form

Expected behavior

value is loaded on form

Runtime

• Elixir version: 1.16.1
• Erlang version: 26
• OS: mac
• Ash version: 3.0.0-rc.36
• any related extension versions
  • Ash Phoenix version: 2.0.0-rc.8

Additional context
Add any other context about the problem here.