Somehow this 1-on-1 chat has stopped working circa 2013 for me. People using google still show up as online in my contact list but do not ever receive my messag

Somehow this 1-on-1 chat has stopped working circa 2013 for me. People using google still show up as online in my contact list but do not ever receive my messages. On the other hand I do not appear in their contact list anymore.