media encoder outputs blank video

Hello,

I have been using a Premiere pro, and media encoder, with sometimes updating the version, for more than four years. I didn't have encountered this kinds of problem and I need some help.

I usually video-edit the lecture videos and give the projects to the media encoder. I copy the introduction part of the video and paste it to the next new project, which is  next lecture. But since a few weeks ago, videos which are encoded after the first one, came out with all black only with sounds.

my output setting is H.264 1920x1080, progressive, nvidia codec, CBR 0.73Mbps.

It does not give any problem when rendering is done in Premiere itself,. but the problem occurs only if I use the media encoder, and it occurs with 2nd video. I tried uninstall-installing of the Premiere and Media encoder but doesn't worked. 

Please give me a help.