I have a kind of same problem in Avast Free Antivirus, in Windows 11 Home.
I think this is a bug in Avast, since we both have the same problems.
You could try some of the methods below:
1) Repair your Avast installation in
AvastUI.exe > Menu > Settings > General > Troubleshooting > Repair App. Note that this might take a while.
2) Do a clean reinstall of Avast using the
Avast Uninstall Utility. When it prompts you to select your product to uninstall, select Avast Premium Security. Then, reinstall Avast Premium Security.
3) If you used other third party antivirus software before, remove all leftovers of them. They might have another uninstall utility. Run that executable. If not, simply go to File Explorer and delete the leftovers of your old antivirus.
If all of these don't work, please leave a reply.