did you import a video file like an mp4, mts , mov or did you open an mvp file or Magix video file when we work with Magix video editor? You can use Windows explorer and select the file you need to open using the right mouse bouton to acess to properties also you can use a free software like media info to see properties.
First, in order to have any chance of being able to help you we need a lot more information; please read this post and make sure you supply everything requested. (We don't know anything about your computer, operating system, nor even which version and variant of MEP you are using.)
Then please tell us a lot more about the actual video file you are trying to import; mp4 is a container format, the actual file can be in various formats so please find and download the free MediaInfo utility, point it at your file and then copy and paste the text data to a post.
When you say your file is "cut off to 31:19" do you mean the remainder of the file up to the original 33:40 is "missing" or is it that the whole file is, effectively, playing faster and hence lasts a shorter time? What settings are you using for your MEP project (frame rate, audio sampling frequency etc.)?