Just for generall information since this issue is not officially documented.
We have several customers that get an Avast password windows during the restart or shutdown of the clients. This issue has been reported from our site on march 26th. Avast support/engeneering is on the issue but I’m wondering what it takes so long to fix this…
Maybe this issue is more common and related to other Avast clients, see https://forum.avast.com/index.php?topic=327551.0?
I can confirm that we have the same issue on our customers. 
I have not had taken the time to check if this problem also occures even set policy without password but I was under the impression that this password window will always appear and is independet of the policy settings, can anyone confirm?
I think that if you are not set a policy to protect the UI with a password (my personal profile), you are not affected by this issue.
The issue is still here.
Any update from AVAST?
Just yesterday but only standard mail macro that they are still working on the case…
Maybe @GeorgeP can get any details here on what is going on?