[DISAPPEARED] Mail Shield does not scan any email

[REDACTED]

Dear all,

I'm running Avast Security on my iMac (macOS High Sierra).
When I open the app, all seems running well. Also File Shield and Web Shield are constantly scanning files.

However, Mail Shield does not seem to scan any email. It's constantly showing "scanned files: 0"

I'm reading my email in Mail (standard Apple mail client).
Mail is connecting to several gmail accounts that I have plus an iCloud mail account.

How to make Mail Shield scanning my incoming emails?

[REDACTED]

Update: I was just about to reinstall Avast, and suddenly it started to scan my mail!
Strange, but the problem seems to be solved.