Looking at DV Im getting:
5121   3.046644   5164   Meli_nt.exe   [st] [netTalk][thread=2] MatchSubjectWithURL [api.mercadolibre.com] =?= [api.mercadolibre.com]
5122   3.047657   5164   Meli_nt.exe   [st] [netTalk][thread=2] Certificate Verified: api.mercadolibre.com = api.mercadolibre.com
5123   3.265226   5164   Meli_nt.exe   [st] [netTalk][thread=2] NetSimple.ErrorTrap 0 Error connecting to Service. Server Response: 400 HTTP/1.1 400 Bad Request
5124   3.265226   5164   Meli_nt.exe   Content-Type: application/json;charset=UTF-8
5125   3.265226   5164   Meli_nt.exe   Transfer-Encoding: chunked
5126   3.265226   5164   Meli_nt.exe   Connection: keep-alive
5127   3.265226   5164   Meli_nt.exe   Date: Mon, 31 Dec 2018 16:34:12 GMT
5128   3.265226   5164   Meli_nt.exe   Vary: Accept,Accept-Encoding
5129   3.265226   5164   Meli_nt.exe   Cache-Control: max-age=0
5130   3.265226   5164   Meli_nt.exe   X-Content-Type-Options: nosniff
5131   3.265226   5164   Meli_nt.exe   X-Request-Id: 6a169c14-c524-4151-9374-f70065cbc5f3
5132   3.265226   5164   Meli_nt.exe   X-Frame-Options: DENY
5133   3.265226   5164   Meli_nt.exe   X-XSS-Protection: 1; mode=block
5134   3.265226   5164   Meli_nt.exe   Access-Control-Allow-Origin: *
5135   3.265226   5164   Meli_nt.exe   Access-Control-Allow-Headers: Content-Type
5136   3.265226   5164   Meli_nt.exe   Access-Control-Allow-Methods: PUT, GET, POST, DELETE, OPTIONS
5137   3.265226   5164   Meli_nt.exe   Access-Control-Max-Age: 86400
5138   3.265226   5164   Meli_nt.exe   Strict-Transport-Security: max-age=15724800
5139   3.265226   5164   Meli_nt.exe   X-Cache: Error from cloudfront
5140   3.265226   5164   Meli_nt.exe   Via: 1.1 92f892199bcce7a13a5283e1376fa0e8.cloudfront.net (CloudFront)
5141   3.265226   5164   Meli_nt.exe   X-Amz-Cf-Id: hHhmUxB0iyTHUon-YEU7oQWDU7aBRV7n2rWXa_TWbgcLniUCC2-GVw==
5142   3.265226   5164   Meli_nt.exe   
5143   3.265226   5164   Meli_nt.exe   {"message":"Wrong number of parameters","error":"invalid_request","status":400,"cause":[]} NetOAuth.PageReceived
See the last line...