So I had sync up and running fine between my PC and Android S+8. I un-synced my android for security purposes, and when I went to resync the phone and add another phone to the devices to sync, it was a no go! You could see the devices in your avast account online, but in avast antivirus you could not see them and you could not find them to activate the devices.
It came down to turning off syn in avast passwords on the pc, when you do that you will be prompted that all passwords will be removed from passwords in avast. They will be gone when you do this but they will be back later (as long as you have your password to re activate your original account).
You must find your original email from avast in case there is a problem, click on the link in the email and reactivate your original account, for me it was my pc. All your passwords and information will be back in your account.
https://support.avast.com/en-us/article/92/Once this is done, on your other devices turn on sync and request activation, they will appear and you can activate them.
Avast has a really good product here if they make it a little more friendly! For someone nontechnical this is completely useless feature/option, and I cant see them using this feature. I would be happy to pay a small per device fee for a more robust program for the passwords, it is a really safe and secure way to have your info available to you.
Good Luck
