I am developing the integration with MercadoPago Connect in my marketplace following the documentation of: link
I get the seller user token perfectly. But when I try to create a payment preference using that token I always get the error message: "Test tokens are not allowed"
I am using the sandbox mode in all cases, and I can not find any steps in the documentation that may be jumping.
To connect the user I have tested with personal MercadoPago users and with test users generated by Curl.
Has this happened to anyone before? Is it that it can only be done in a productive way?