I was very much looking forward to the 3.0 update because v2.8 was causing certain movies of varied formats to freeze on startup.
v3.0 seems to have fixed that issue but now I find that many movies in avi, mkv and mp4 formats suddenly have NO AUDIO AT ALL! ZERO SOUND.
Their audio is fine on v2.8.
I'm on a mid 2010 21.5" iMac with the latest macOS High Sierra 10.13.3.
I do hope you can track down and solve this problem speedily.
All the best.