I was just messing around with PD and mkv files as previously when I tried it would not open the files. I am seeing a pattern in what will work and what won't work. It seems dvd to mkv files work just fine but blu-ray to mkv files do not work. Perhaps this is a size issue? The dvd to mkv files are generally in the 3.5gb to 6gb size but blu-ray to mkv files are in the 25gb to 35gb size.
I also noticed that wtv files now also appear to be editable as well.