Microsoft Oauth refreshing token getting 404

Question

Following Microsoft Oauth docs, I obtain the first access token and the refresh token using offline_access in the scope like this:

But, when I try to do the refresh token call, using that same refresh token I got there, I got a 404 :

Already tried adding the tenant ID in the POST url like this:

https://login.microsoftonline.com/{mytenantid}/oauth2/v2.0/token

But got "invalid url" error...

Any idea ?, does the first token have to expire in order for this to work ?