I put .obj files for a building into a folder that has other .obj files of other buildings I have used in the past, but when I go into Daz, I can find the folder, but not the files within.
Yes, that’s right. The .obj files are not supposed to show up in the same way as D|S or Poser files — also, you can’t put these files just anywhere, they’re supposed to be in a folder inside the /Runtime/Geometries/ folder, where are you putting them?
It also matters how you’re looking for the folders, is it in the Content Library tab, or Smart Content, or a category view? None of these work for an .obj file, they don’t get loaded as content, they get imported (File menu>Import). So exactly what are you doing between “go into DAZ” and “find empty folder”?