I sent the recommendation link to my friend and he installed Avast Free Antivirus and all the rules were respected but on the app it still appears 0 friends installed it (he even sent me photos of the app installed).
I don’t know if there is some sort of delay before it is credited or not. Otherwise what is to stop installing and promptly uninstalling it.
Though if my memory serves me well, I think I have see one or two similar topics recently.
I see you have found one of the topics I mentioned, https://forum.avast.com/index.php?topic=252142.0
Keep monitoring that one as it has been reported to avast by one of the Avast Überevangelists in the forums.