API Access Issue: POST /bill/{id}/trackings returns 40

Dear Delcampe API Support Team,

We are a professional seller on Delcampe (account: prophila) with an active API Pass subscription. We are currently developing an automated tracking number submission workflow using the REST API.

We are attempting to use the following endpoint to submit tracking numbers:
POST Vinculo (https) =...

However, we consistently receive a 403 error with the message "You're not allowed to view trackings for this payment request", even when using a valid bill ID that belongs to our own account.

We have verified the following:
- Our API token is valid (GET /seller returns HTTP 200 with our account data)
- The bill IDs we are using belong to our account
- GET Vinculo (https) =... returns HTTP 200 with full bill data
- GET Vinculo (https) =... returns HTTP 200 but with a 403 status in the response body
- POST Vinculo (https) =... returns HTTP 200 but with a 400 error when we omit fields, suggesting the endpoint exists but we lack write permission

Our question: Is the POST /bill/{id}/trackings endpoint available for our API Pass subscription level? If not, what is the correct endpoint or procedure to submit tracking numbers programmatically via the API?

Thank you for your assistance.

Best regards,
Prophila Handelsgesellschaft mbH