[4.x]: GraphQL mutation: "We couldn't find any matching entries" when creating entry with relational fields

What happened?

Description

When trying to create an entry with relational fields via a GraphQL Mutation, I got the message "We couldn't find any matching entries". It seems that the corresponding relational entry doesn't exist. But it does definitely.

When updating the entry (while passing the entryID to the mutation), it updates the relational field with the corresponding entry.

The strange thing is that it's working in graphiQL when passing all the necessary arguments except the entryID, but not in local. We also checked all the necessary permissions both in the schema and the user.

Steps to reproduce

1. Create a mutation that saves an entry

mutation saveOffer(
    $id: ID,
    $title: String,
    $activityIds: [Int]
  ) {
    save_offer_default_Entry(
      id: $id,
      title: $title,
      activity: $activityIds
    ) {
      id
      title
      activity {
        ...on activity_default_Entry {
          id
          title
        }
      }
    }
  }

2. Call this mutation from the front end while creating a new Offer

const { data, errors } = await saveOfferMutation(authCookie, {
  title: 'test offer',
  activityIds: [121183]
});

=> message: "We couldn't find any matching entries",

3. Call this same method for updating an offer :

const { data, errors } = await saveOfferMutation(authCookie, {
  id: '121533',
  title: 'test offer',
  activityIds: [121183]
}); 

=> Works perfectly.

Expected behavior

Mutation to create an entry with relational fields while passing the relational field ID to work.

Actual behavior

Not working.

Thanks guys!

Craft CMS version

Craft Pro 4.8.9

PHP version

8.1.27

Operating system and version

Linux 4.19.0-22-cloud-amd64

Database type and version

MariaDB 10.4.33

Image driver and version

Imagick 3.7.0 (ImageMagick 6.9.10-23)

Installed plugins and versions

Start by reproducing the save_offer_default_Entry GraphQL mutation from the issue against Craft CMS 4.8.9, comparing creation with the working update case and the frontend saveOfferMutation call. Trace the relational-field ID handling and verify that creating an entry with activityIds succeeds without the matching-entries error.