Can convert only mp4 video files

I am using ClipBucket 4.2 for my video streaming site.
When I check the Stay MP4 as it is, mp4 files were uploaded successfully.
But if I uncheck it, any video files including mp4 ones would not be uploaded at all.
But notification says “The video was uploaded successfully.”
So when I go to the files folder, there is an empty folder without any video content.
Please help me!!!