I have a mechanical chime; this was all working fine till recently.Have you tried a different player? I just opened VLC to double check mine.
Open Network >
rtsp:/admin:password@192.168.X.Y:554/cam/realmonitor?channel=1&subtype=0#backchannel=0
Obviously replace password and the IP with yours.
Maybe it's the software?
In case it's relevant, I have a mechanical chime attached to mine although I doubt that makes a difference.