This has happened with multiple artifacts (not in a row but over this past couple days) where when attempting to upgrade an artifact, it will take the silver but not show any upgrades to the stats. With the first couple artifacts, all it took to fix was to back out of the upgrade menu and it showed the proper upgrades. With the artifact I tried to upgrade today, it never showed the upgrades even after relogging. The silver cost was still increasing and at some point it was acting like it got past the level 4 upgrade because it started to fail some of the upgrades.