I created a GEDCOM file using Family Tree Maker 2019 and imported it using the Rootsfinder GEDCOM Importer. For some reason the importer imported only 3,183 media files out of 3,369 files referenced in the GEDCOM file and contained in the FTM media folder. Haven’t been able to find anything that might cause this.
I’m not sure why the other files didn’t get uploaded. Have you been able to find a file that wasn’t uploaded? If you will send me the gedcom (dallan at rootsfinder.com) and the name of one or two of the files that didn’t get uploaded, I will look into it.