Cognito TOTP MFA issue

Hello,

I am trying to integrate AWS Cognito to my Java application and I am facing some issues with TOTP MFA. More specific:

AWS Java SDK version
1.11.755

Cognito configuration
1. Users sign in using email address
2. Sign up is only allowed by administrators
3. MFA is optional and only TOTP is supported
4. An application client is created without secret, which only supports ALLOW_ADMIN_USER_PASSWORD_AUTH authentication flow

Process
1. I create a user using the adminCreateUser function
2. I try to login using the adminInitiateAuth function. The first time I login when MFA is not yet enabled, I get the relevant tokens successfully, without having to respond to an authentication challenge (i.e. SOFTWARE_TOKEN_MFA )
3. I enable the MFA to the created user using the adminSetUserMFAPreference function. I set the software token MFA as preferred and as enabled. Also, I execute the associateSoftwareToken function to get a secret, in order to use it in the authenticator application.
4. I try to login using the adminInitiateAuth function expecting that I will receive in the response the SOFTWARE_TOKEN_MFA challenge, but this does not happen. I get the relevant tokens and no challenge (like MFA is disabled). I verify at the user information that the MFA is correctly set.

I do exactly the same process using SMS as MFA method and the behavior is the expected one. In step 4 (i.e. sign in after MFA was enabled), I get the SMS_MFA challenge.

Can you please elaborate why is this happening? Is something wrong in the process I am following?

I tried also to use the ALLOW_USER_PASSWORD_AUTH authentication flow (via initiateAuth function), for the login of the user but the result was the same.