If you compress and convert a video using Clipchamp Utilities and notice that the finished output video length is shorter than your original input file length, i.e. parts of the video are missing, there is a high chance this is due to incorrect timecodes in your input video.
If the time stamps in your input file are broken, Clipchamp thinks that it reached the end of the file too early and thus finishes the processing prematurely. This can be a problem with MPG or VOB video files in particular.
In order to process files like this successfully, you need to fix the timecodes before converting the video.
There are specialised applications available that allow you to correct time stamps or timecodes. Search for a term like "fix broken timecodes" online to find one.
Once you have corrected the timecodes, you can compress the resulting video in Clipchamp Utilities.