Facebook "via" acknowledgements

I post a lot of links, pics and viedos on my Fb page. Friends re-post (share) some of these on their own pages. Until quite recently, I would get a notification that said "X has shared your link" and when it appeared on their page, it would say "link via Alison". But recently it just says "X shared a link" and on their page the link appears without anything about who sent it to them. What has changed, or what are my friends not doing? Facebook provides a "via" feature to allow people to acknowledge their friends but this new behaviour seems to violate that. It makes me less keen to post things.