There is some quantum behavior in copr when observing the build destroys the easy access to build artifacts.
When you run a build in copr and want to take a look at artifacts while the build still runs, it's possible. It however affects how the artifacts will be displayed later.
In the linked build, I've taken a look at the files when the build was in state "running" by clicking on chroot fedora-rawhide-x86_64. There was only one file at the time.
The build ended successfully, yet the results were not populated under this link. There is still the one file that was in the moment of first check.
To get the full build logs, one has to go a level up in directory structure and find the exact build number there. For mass actions and many repetitious builds of the same package this can be tedious.
If you don't observe the results while running, the results are populated under the chroot link correctly, like in the other reference build.