acme challenge deleted before verification

[Meidan]

all my verification calls return a 404, so I started looking into the container wwwroot and I saw that the acme challenge is created under /usr/share/nginx/html/.well-known/acme-challenge/ but it is removed before the verification call on it is made.
Is this some configuration? I'm not overriding any defaults.

error I get is:

13:10:10 Obtaining a new certificate
13:10:11 Performing the following challenges:
13:10:11 http-01 challenge for <MyDomaon>
13:10:11 Using the webroot path /usr/share/nginx/html for all unmatched domains.
13:10:11 Waiting for verification...
13:10:11 <IP> - - [11/Jan/2019:18:10:11 +0000] "GET /.well-known/acme-challenge/<ChallengeKey> HTTP/1.1" 404 162 "-" "Mozilla/5.0 (compatible; Let's Encrypt validation server; +https://www.letsencrypt.org)" "-"
13:10:58 Cleaning up challenges
13:10:58 Incomplete authorizations