I'm using a local network streaming. Sometimes the streaming stops, because my cable tv box gets slow or something (still trying to figure it out), but when the playing resumes, sometimes a few seconds later, the sound doesn't come back, I get only the video playing. To fix it I have to close the player window and open it again and I get the sound back.
macOS 10.14.5
VLC 3.0.8
I just upgraded from V2 and it this was not happening with that version, looks like a V3 bug.