Just updated vlc to 3.0.3. Now when I plug in HDMI (Laptop to TV) the window does not expand properly to fill my TV. I have to close the file entirely and then re-open for it to show full-screen properly.
I've used VLC for years but this problem has gotten so bad I just had to switch players. Can confirm that the .mkv files play completely fine in other players including potplayer, MPC-HC (an outdated player) and DivX (must pay for full features). The problem therefore lies with VLC itself.