question

I created a User Flow on my Azure Active Directory B2C with the "Sign in using resource owner password credentials (ROPC)" type. I followed all the doc steps, but I'm receiving 404 status code as response with the following message:

The resource you are looking for has been removed, had its name changed, or is temporarily unavailable.

I've already read some similar problems but no one of their solution had solved my problem:

• StackOverflow: 404 Not Found error via resource owner password credentials flow in Azure AD B2C
  

• MS Docs Q&A: Custom policy in Azure AD B2C throws an "The resource you are looking for has been removed, had its name changed, or is temporarily unavailable.
  

• MS Docs Q&A: The resource you are looking for has been...

Note: I'm not using any Custom Domain, I still using the default one "my-tenant.onmicrosoft.com"

That's the way how I'm trying to validate the ROPC User Flow:

 curl --request POST \
   --url 'https://my-tenant.b2clogin.com/my-tenant.onmicrosoft.com/oauth2/v2.0/token?p=b2c_1_ropc_auth' \
   --header 'Content-Type: application/x-www-form-urlencoded' \
   --header 'Host: login.microsoftonline.com' \
   --data client_id=<my-client-id-goes-here> \
   --data 'scope=openid <my-client-id-goes-here>' \
   --data grant_type=password \
   --data username=username@gmail.com \
   --data password=StrongPassword@123 \
   --data response_type=token

What am I doing wrong?

 curl --request POST \
   --url https://my-tenant.b2clogin.com/my-tenant.onmicrosoft.com/b2c_1_ropc_auth/oauth2/v2.0/token \
   --header 'Content-Type: application/x-www-form-urlencoded' \
   --header 'Host: login.microsoftonline.com' \
   --data client_id=<my-client-id-goes-here> \
   --data 'scope=openid <my-client-id-goes-here>' \
   --data grant_type=password \
   --data username= username@gmail.com \
   --data password=StrongPassword@123 \
   --data 'response_type=token'