Many-to-many manage_relationship renders nested UUID "Id" inputs instead of relationship selector (label_field ignored)

[fbutano]

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Versions

•	ash_admin: 0.13.24
•	ash: 3.11.3
•	ash_phoenix: 2.3.18
•	ash_postgres: 2.6.27
•	ash_authentication: 4.13.4 (installed in repro, but not required for the admin form)
•	phoenix_live_view: 1.1.19
•	phoenix: 1.8.3

Operating system

macOS Tahoe 26.1

Current Behavior

In AshAdmin, a many_to_many relationship managed via manage_relationship in a create/update action renders as a nested UUID "Id" input (i.e. "Office Ids -> Id"), instead of using a relationship selector (dropdown/typeahead) that displays records using the destination resource label_field.

Reproduction

Reproduction repo
https://github.com/fbutano/demo_admin

Steps to reproduce

1. mix deps.get
2. mix ecto.create
3. mix ash.migrate
4. mix phx.server

Then:

• Open AshAdmin (see repo/router setup)
• Create a couple of Office records
• Go to User -> create or update

Expected Behavior

For the User.offices many-to-many relationship (through Membership), the form should render a relationship selector (dropdown/typeahead) and display Office records using:

admin do
label_field :name
relationship_select_max_items 10
end

[zachdaniel]

Well, looks like I was wrong about this being supported, and it's currently only supported for belongs_to relationships? I'm honestly so strapped for time I can't look into it beyond that right now. Might be worth checking to see if it works for has_many relationships. AFAICT it's only implemented for belongs_to. So PRs welcome!