I have been seeing this bug for a long time. In the Great Works screen in the unthemed Art Museum sections (and also in the tourism lens when hovering over the respective Theater Square), the Great Works of Art tourism is not calculated properly - in fact, it is lower than it should be (at least when running the Heritage Tourism policy card). The culture is also incorrectly shown. Please correct it finally because it makes Art Museums even less worthwhile for Culture Victories. One more thing is not fixed yet: the artifact era shown before choosing the civ the artifact orginates from occasionally differs from the actual artifact era shown next. Please fix it so that we can plan the Archeological Museum theming better.