Client Live Preview not working, fieldSchema is empty

[lsdebianchi]

Hello,

I am trying to make client live preview work.
I followed the docs (https://payloadcms.com/docs/live-preview/client) and built the custom listener (using @payloadcms/live-preview as I am in Sveltekit).

The basics are working. I send the ready signal, and the parent iframe answers. I edit the field in the admin UI and iframe messages are being sent. My client site catches them, and they indeed contain the updated data.

But then the subscribe function from @payloadcms/live-preview returns me a mergedData which is always equal to the initialData, even if the iframe messages received have new data in them.

On my side I see that is the mergeData() step which is not applying the new data. Looking at the source code I see that the result is populated by this fieldSchemas.forEach inside traverseFields.

I check the fieldSchemas I receive at this step and it's indeed empty [ ].

I am trying to read the source code to try to understand why, but I am out of my depth.

Configs for the given page:

export const EasyPage: GlobalConfig = {
  slug: "easyPage",
  admin: {
    hidden: ({ user }) => user?.role !== "dev-admin",
    livePreview: {
      url: "http://localhost:8080/easy?preview"
    }
  },
  access: {
    read: () => true
  },
  fields: [
    {
      type: "text",
      name: "title"
    }
  ]
};

Payload & @payloadcms/live-preview version: 3.50.0

Anyone know what could be the reason for it?