Music files not showing up

I am moving MP3’s from a third party downloaded folder to my USB drive, but cannot get all of the songs into the folder in the USB. When I try to add them in it says that the songs are already there and either to skip, stop the action or replace the song. I initially tried to just click replace all, but I have different songs of the same name and they both don’t show up anyways. It says that my songs are in that folder, but when I add them in one by one I can see them be added and then disappear… ?? like it just goes away. My USB drive is 256G and I have about 8G of music in there so that can’t be the reason. Cant help but think this is just Apple being Apple, but any help would be greatly appreciated.