I’m not sure if this is the case, but try to update to the latest Anki version (2.1.29).
If it doesn’t help, open the Debug Console - https://docs.ankiweb.net/#/misc?id=debug-console - copy-paste the following lines and press Ctrl+Return or Cmd+Return if you’re on Mac.
Try to review a few cards with audio and if audio stops playing, look at the last lines in mpv.log.txt
on Desktop, maybe it’ll give some idea what’s going on.
from aqt.sound import mpvManager
path = os.path.expanduser("~/Desktop/mpv.log.txt")
mpvManager.set_property("log-file", path)
print(mpvManager.get_property("log-file"))