I paid for the MPEG4 addition and it said it successfully loaded but I still cannot open MP4 videos in Magix Movie Studio Pro 14. Only get black screen. Any suggestions or ideas will be appreciated..
Hello Dave and welcome to the forum. I was the one who suggested you come here.
Early Magix editors don't handle MP4s as well as the later versions but you never know your luck. The new versions are very much improved over MEP 14 in file handling and processing speed, depending on your computer.
First step: exactly what name and version do you have? You can get those from the Help menu>About.
If it is "Magix Movie Edit Pro 14", could you provide some file details from a file-analysis program called MediaInfo.
Also, it would be great if you could give us a sample file hosted on Google Drive, Dropbox or similar. Google Drive procedure here.
You could try rewriting the file header with AVIDemux by doing a lossless save procedure as I describe on my website here. I know your file is already MP4 but it may work.