Plug in only syncs 9 files and then stops

I apologize in advance, I am not an experienced WordPress user. I am trying to stage a development environment for the website I administer. I’ve copied over the uploads directory from my production environment. When I run Media Sync it copies 9 files to the media library and then stops copying. The spinner icon keeps rotating but no additional files are moved to the Media Library. I’ve tried several times and each time it copies 9 files and then stops. If I do a “Dry Run”, it goes through the entire list, but when I try to do the actual sync, it stops at 9 files (I can tell because counter “Imported 0 out of 653” decreases by 9 each time I run it. I tried to paste a screen shot of what I’m seeing into this message but it doesn’t work with a simple copy and paste. I know I haven’t given you much information. Please let me know what I can provide that might help troubleshoot this.