The account you are logged into on the Alexa app might be different than the specified provisioning account in the AIPEX portal (shown under Account → Settings). Try saying "Alexa, what account am I in" to that specific device. It should say: “I’m not sure who’s speaking, but you’re in <first name’s> account. To teach me to recognize your voice, just say learn my voice.” the <firstname> spoken should be the one assigned to your Amazon provisioning account You can see the firstname that you used when you created the account by logging in to the amazon.com
retail site with that account, then 'Your Account', and then 'Login and Security'.