I am having two different problems, I will try to explain both them as best as I can.
I've been burning anime just fine, with ConvertXtoDVD, for a few months. Recently I got the newest release of a series, and I tried to burn it. I always have it to burn the finished product as an ISO file, so I don't end up wasting any blank DVDs. Anyways, I did everything the same as usual with the new episodes. After it finished I opened the ISO with Deamon Tools Lite, and everything seemed to be fine. I tried skipping through the episodes and it didn't seem to work quite right with the second episode on the disc. Whenever I skipped near the end; it would go back to the second chapter in the chapter menu, but the audio would play normally. I messed around with it some and it went to the next episode, but it was just frozen there. What could be causing this, could the new episode I got be corrupt or something?
Now for the other problem, with a different anime. I burnt the first few episodes just fine, and everything seemed to be doing well. I decided to burn a few more, but when I tried to ISO the audio was in Japanese rather than english. In the main menus it's set to use english for the default. I looked through all the videos, and they do have an english audio track. I went down through each video and checked the default audio box beside the english audio track and it still didn't work, the Japanese audio track was still the default whenever I tried the finished ISO.
The video files I was burning were in MKV format, which is what pretty much everything I've burnt has been in. Again, the two problems were happening with two different series and I didn't have the problems with earlier episodes in the series. If anymore information is needed I'll be glad to add it.