When experiencing bugs in Xfce4-notifyd, your way of helping things getting fixed is to report a bug about it in bugzilla. Note: For this you will need to have/create an account.
Here's a list (updated daily) of open bugreports with the date that bug was reported in brackets. To see the full list via bugzilla, go here.
If your bug/problem has not been reported before, report a new bug. Please ensure that you disclose any information that might be relevant for developers reading the bugreport, e.g. what distribution you're using, what package-version or what version of libnotify etc. To report a new bug, go here.