No, this is not fixed & would hope that Avast do something useful about this, ie:
Clean Install, latest version of Avast Premier. LAN set to Private Network.
Other Network PCs cannot be seen, files & dirs not shared etc.
Turn off Avast firewall and they can. This is consistent.
The one preference that allows (some) access is to turn ON Firewall /Internet Connection Sharing Mode. However, of course this seems to be a kludge & is not what that preference is intended for, ie: I do not want or need to share Internet connection, rather, simply share files on a Home Private LAN.
Further, if AVAST is bypassed completely, I can also see a share MacOS computers on the same network; also see and access other peripherals such as LAN router, NAS, Apple TimeCapsule etc.
Finally, while we're at it: is impossible to access TV Chromecast without turning off AVAST Firewall. In all cases as per above, the built-in Windows Security & Firewall functions perfectly.