With this new Avast and the old Avast, I would have to start the anti-virus manually.
I uninstalled and reinstalled to see if there was a problem in the first installation.
Is there a setting to make Avast start on boot up?
Have you tried this? https://www.avast.com/faq.php?article=AVKB204#artTitle
If Repair doesn’t fix the problem, try the following:
Clean Install of Avast:
https://goo.gl/4Ptzkf
If you need additional help with the Clean Install, watch this:
https://youtu.be/p-h3myRD51A