I tested a load of different formats and basically, on my system, VP14 is just ignoring the "Automatically save trimmer markers and regions with media file" preference being unchecked and saving them anyway:
IMO quite dangerous in the case of those MP4 formats at the top of the list. I don't want any software putting metadata into my original files unless I tell it to.
I'd prefer that markers be saved in SFL files for all formats. I also don't like when they are saved in media files.
Vegasaur, is there anything you can do about the mess of the markers being saved properly in Vegas. I've given up on Magix solving the marker mess. Hoping that you can figure out a way to make it work.