After a search for an artifact that provides results from different repositories (here one proxy and one hosted), there's a pick list labeled "Viewing Repository:" which contains the different repositories concerned by the search.
See in the attached image that by choosing the version 1.15.0-SNAPSHOT which is contained in the hosted repo, I have by default selected the proxy repo. It lists the artifacts available but not my artifact. I have to select the other one to display it.
This pick list should be in the upper section to filter results (show only results within one of the repo and have a "all" entry as well) or should change its default selection when the user choose a different entry in the search results.