@LLLLllllLLLlll if you're mounting the drive already you don't need to use usbromservice.
Are you saying that I should just manually set things to point to the drive folder if I'm mounting the drive elsewhere? Everything's currently at ~/RetroPie on the NUC's internal drive. I could manually move it all to the external and set configs to point there (assuming I don't miss anything), I just figured that was the point of usbromservice.
I was instructed in one of the threads on here to make an alias to the folder on the usb drive containing the roms and just replace the folder in the retropie roms folder with the same named alias. That also works. One thing that I like about that is I could at any time just delete the alias and replace with a folder to return it to reading off the sd card, or you could have part of a folder on the usb and part on the sd (if you don’t mind having two subfolders in ES).
I think there's something wrong with the version you have, because the RetroPie 4.5.1 image doesn't support the PI4 model (!). So which RetroPie version do you have ?
As noted in https://retropie.org.uk/forum/topic/3/read-this-first, support for PI4 is still added to RetroPie so some things are not fully working - certainly not using the 4.5.1 version.
EDIT: you can see the exact version by looking in the RetroPie-Setup script title:
So I finally figured it out. As usual it was a couple things, but none of them were as difficult as I was looking for. Everything was a little out of date, and because I was working on wifi, i figured id let it update everything over night. Turns out I hadnt done that since enabling usbrom service. After the update it (mostly) solved my problem, and after putting the pi on stretch instead of Jessie I'm good. Thanks @Efriim for going down the rabbit hole with me. I appreciated your help
@che_don_john Ahh..gotcha..I was just curious. I see alot of people transferring via usb and have problems. So much easier using ssh. I was one of them when I first got my pi as I watched a youtube vid with no knowledge of ssh, and I found it took forever to transfer games via usb..lol . Glad you got it sorted !
Just put a folder called retropie-mount and a Roms folder. As long as those are there, it won’t copy anything. If you don’t have a Roms folder it will copy the roms folder from the sd to the usb memory.
Made some progress. Formatted the drive to NTFS and that sped things up considerably. I assume the wiki uses FAT32 specifically for flash drives and windows compatibility, though I'm not sure why they don't suggest exFAT.
Right now I'm working on testing if exFAT is faster or slower than NTFS.
I wish I'd known the usbromservice was more accepting of different file systems from the get go.
AlexMurphy is right, check out that link. It very well could be (as the link states) that your power supply isn't providing enough current. Also, if you are running a pi 3, if my memory serves me, wifi is built in. You not giving us any base information to work with makes things difficult to help.
Also, if a better power supply doesn't work, I'm guessing that it's a hardware issue, not software, in which case, this is probably the wrong place to ask.
After deleting all folders in the retropie-mount folder on the stick and plugging it in on the rasperry and rebooting the system it seems that it starts copying again. Now everything seems to be copied correctly. The retropie menu is now here as well.
Sorry for the big panic from me. Everything is fine now.