Bought a tracker a few days ago and couldn't finalise the installation on the application. All the settings are correct: the account, Bluetooth that recognises the tracker, device properly charged, validated for use in Switzerland!
I'm in email contact with Invoxia France who have asked me for a copy of my invoice ..... I'm waiting for their next reply.

Does the phone app find the tracker when you are nearby? Bluetooth must be switched on on the phone. If so, check under Settings whether an update of the tracker software is offered and carry it out. After a while, the tracker should send its position normally again.