If you use an old account with an already registered device or created a new one and you have no problems creating a unit, therefore, whether your tracker is working with a new application is not connected in any way with the old application.
When you configure the tracker using SMS, do you get any answer about the success of the comands? If not, then you need to see the instructions for your tracker.
If yes, then try to request data on the port, server, time and location via SMS from the tracker, and check that they are right.
Also check that the tracker has the setting and data transfer frequency turned on (in some trackers this needs to be done additionally, since the tracker can be configured correctly, but not send any data)