We need some advice ASAP

We have submitted this both as a ticket and a post on the developer's forum. If anyone can suggest some solution that, we would greatly appreciate it. Our timeline is very tight to resolve this:

We are building a mobile app. Once a survivor signs up, The user should be added as a subscriber based on the user type the user chooses.

Our develop uses this code:

$array_list= array(1,8);
TNP::subscribe(['email'=>$email, 'name'=>$fullname, 'lists' =>$array_list])

After the code is executed, it adds the user to the user list:

But the user is not added as a subscriber

The user does receive a welcome message sent by the Newsletter plugin

Please advise.