Hello kloyner,
Thank you for your post.
Please specify what command line parameters you use for we could help you. What task are you trying to do using the command line?
Please make before the file opening the file via command line the following setting: Tools / Preferences / Control / Synchronize media library list with files on timeline. Close the Video Splitter and try to open the file via command line again. In this case the file will be opened in the timeline.