It’s pissing me off. I have to turn it on manually every time.
I’ve been using Avast for many years and now I’m thinking about using another antivirus software if this issue cant be fixed.
What OS are you using? (Had the same problem with one or multiple shields on a Vista computer.)
And did you wait a few minutes to see if it eventually goes on by itself?
Hope this answers your question:
https://forum.avast.com/index.php?topic=205855.msg1412140#msg1412140