I was having the same problem with my new GS7. Finally figured it out.
I had my PC up and on my GS7, wen tto the Syc and back up tab. When it had the code for my, at the bottom of that screen there is a logout and quit (something like that). Once it logged me out (and there was a notice about deleting passwords on my device, I clicked OK) I shut down the app, then restarted it. Logged in with my AVAST Web account username and password, then I was finally able to get to the Sync and backup screen. It showed my a list of authorized devices, (I removed my old cell phone, since it's not working anymore,) then back at the app's main screen clicked on the three dots in upper right, and sync was listed. Clicked on it, and now I have my passwords that were strored!
Hope this works for you.