Issues with "edit audio to video"

I am relativly new the the Adobe Audition, but i'v been having 2 issues I can't seem to figure out. The first is when I import a video to "edit audio to video" it doesn't import the entire file, it's always missing a piece. I'v tried multiple time with the same file that is not corrupt and is only 9min long, yet every time it cuts it at a different part, it even cut a section from the beggining of the clip at one point.

Besides that issue, when trying to edit the audio and watch the video at the same time, the video doesn't ctually play, if I pause and resume it will play for just 2seconds and freeze, so I can't actually check if the video and audio are lined up correctly. Has anyone had these issues before? or does someone know how to fix these issues?

also I can't figure out how to export in Mono, all the tutorials ive watched don't work, I converted my track from stereo to mono on the waveform, but when exporting it only gives me the option of stereo