Action pinging Lichess not working, but tested in Postman

I’m having trouble with a custom GPT I’m making. The GPT is meant to start a chess game with the online service Lichess. In this case, I’m making challenges to one of three bots, and setting the time controls to be the maximum (clock.limit and clock.increment).

When I make this request in Postman, it works as expected. Here’s the cURL request:

curl --location 'https://lichess.org/api/challenge/maia9' \
--header 'Content-Type: application/x-www-form-urlencoded' \
--header 'Authorization: Bearer YOUR_PERSONAL_ACCESS_TOKEN' \
--data-urlencode 'rated=false' \
--data-urlencode 'clock.limit=10800' \
--data-urlencode 'clock.increment=60'

When I trigger the action from my GPT, however, clock.limit and clock.increment don’t get set correctly - it seems like they don’t get set at all, as they fall back to their defaults.

Here is what I have in my GPT:

openapi: 3.0.0
info:
  title: Lichess Challenge Bot API
  description: API for creating challenging maia bots on Lichess.
  version: 1.0.0
servers:
  - url: https://lichess.org/api
    description: Lichess API server
paths:
  /challenge/{botname}:
    post:
      operationId: challengeBot
      summary: Challenge a maia bot on Lichess to a game.
      description: Sends a challenge to one of the three maia bots on Lichess with maximum time controls.
      parameters:
        - name: botname
          in: path
          required: true
          description: Username of the player to challenge.
          schema:
            type: string
            default: maia1
            enum: [maia1, maia5, maia9]
      requestBody:
        required: true
        content:
          application/x-www-form-urlencoded:
            schema:
              type: object
              properties:
                rated:
                  type: boolean
                  enum: [false]
                  description: The game is not rated.
                clock.limit:
                  type: integer
                  enum: [10800]
                  description: Time limit set to 10800 seconds (3 hours).
                clock.increment:
                  type: integer
                  enum: [60]
                  description: Increment set to 60 seconds per move.
      responses:
        '200':
          description: Challenge sent successfully.
        '401':
          description: Unauthorized, invalid or missing access token.
        '404':
          description: User not found.
      security:
        - bearerAuth: []
components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
  schemas: {}

What am I doing wrong?

I updated the first parameter to be username as that matches the Lichess documentation but the problem persists…