Hello,
I recently installed Avast Free for my MacOS. I did a couple of eicar test files, however, I noticed that the file shield was able to detect the test file, however, some of the web-based tests were not being detected. I tried reinstalling avast and reallowing avast to have access to the full system, but unfortunately, that did not resolve the issue with the web shield detecting malicious web activity or downloads. There were other sites that I tested the web shield on, but still the same result with the file shield detecting the test malware, but not the web shield.