I started working on this too. When I rip to MKV, it's fine, but when I extract the h264 stream and when I insert into Premiere, it plays like garbage, often with missed or repeated frames. I'm glad I'm not the only one as I was starting to question my computer.

Any idea what's causing this?

The ripped video stream seems to be correct about 98% of the time, but several times over the course of the film, some frames are duplicated, and then later on, some frames skip, bringing it back into sync.